ORACLE QUESTION BANK AND ANSWERS

1. What is RDBMS? What are different database models? RDBMS: Relational Database Management System. In RDBMS the data are stored in the form of tables i.e. rows & columns.

The different database models are 1. HDBMS = Hierarchical Database Management system. 2. NDBMs = Network Database Management System. 3. RDBMS = Relational Database Management System.

2. What is SQL?

SQL stands for Structured Query Language. SQL was derived from the Greek word called "SEQUEL". SQL is a non- procedural language that is written in simple English.

3. What is a transaction?

Transaction is a piece of logical unit of work done between two successive commits or commit and rollback.

4. What is a commit?

Commit is transaction statements that make the changes permanent into the database.

5. What is a Rollback?

Rollback is a transaction statement that undoes all changes to a savepoint or since the beginning of the transaction.

6. What is DDL?

DDL - Data Definition Language. It is a set of statements that is used to define or alter theUser_defined objects like tables, views, procedures, functions etc.,present in a tablespace.

7. What is DML?

DML - Data Manipulation Language.

It is a set of statements that is used for manipulation of data.

E.g. inserting a row into a table, delete a row from a table etc.

8. What is locking?

The mechanism followed by the SQL to control concurrent operations

On a table is called locking.

9. What is a Dead lock?

When two users attempt to perform actions that interfere with oneanother,this situation is defined as Deadlock.

E.g.: - If two users try to change both a foreign and its parent keyvalue at the same time.

10. What is a Shared Lock?

The type of lock that permits other users to perform a query, butcould not manipulate it, i.e. it cannot perform any modificationor insert or delete a data.

11. What is Exclusive Lock?

The type of lock that permits users to query data but not changeit and does not permits another user to any type of lockon the same data. They are in effect until the end of the transaction.

12. What is Share Row-Exclusive lock?

Share Row Exclusive locks are used to look at a whole table and toallow others to look at rows in the table but to prohibit othersfrom locking the table in Share mode or updating rows.

13. What is Group - Functions?

The Functions that are used to get summary information’s about group Or set of rows in a table. The group functions are also termed as aggregate functions.

Following are the examples of aggregate functions:

1. AVG () - To find the average value 2. MIN () - To find the minimum value of the set of rows. 3. MAX () - To find the maximum value of the set of rows. 4. COUNT () - To find the total no of rows that has values. 5. SUM () - To find the summation of the data of a given column.

14. What is indexing?

An index is an ordered list of the contents of a column or a group ofcolumns of a table.By indexing a table, it reduces the time in performing queries, especially if the table is large.

15. What are clusters?

A Cluster is a schema object that contains one or more tables that haveone or more columns in common. Rows of one or more tables that sharethe same value in these common columns are physically stored togetherwithin the database.

16. What is a View?

View is like a window through which you can view or change the information in table. A view is also termed as a 'virtual table'.

17. What is a Rowid?

For each row in the database, The ROWID pseudo column returns a row'saddress. ROWID values contain information necessary to locate a row:

* Which datablock in the data file* Which row in the datablock (first row is 0)* Which data file (first file is 1)

Values of the Rowid pseudocolum have the datatype ROWID.

18. What is a PRIMARY KEY?

PRIMARY KEY CONSTRAINT:

1. Identified the columns or set of columns, which uniquely identify each row of a table and ensure that no duplicate rows exist in the table.2. Implicitly creates a unique index for the column (S) and

specifies the column(s) as being NOT NULL.3. The name of the index is the same as the constraint name.4. Limited to one per table.

Example:CREATE TABLE loans (account NUMBER (6),

loan_number NUMBER(6), ...

CONSTRAINT loan_pk PRIMARY KEY (account, loan_number));

19. What is a Unique constraint?

UNIQUE Constraint:

1. Ensures that no two rows of a table have duplicate values in the specified columns(s).2. Implicitly creates a unique index on the specified columns.3. Index name is the given constraint name.

Example: CREATE TABLE loans (

Loan_number NUMBER (6) NOT NULL UNIQUE, ... );

20. What is the difference between a unique and primary key?

The Primarykey constraint is a constraint that takes care maintaining the uniqueness of the data, enforcing the not null characteristic,creates a self-index.

The Unique key constraint maintains only the uniqueness of thedata and does not enforce the not null characteristic to thedata column. 21. What is a foreign key?

FOREIGN KEY Constraint:

1. Enforces referential integrity constraint, which requires that for each row of a table, the value in the foreign key matches a value in the primary key or is null.2. No limit to the number of foreign keys.3. Can be in the same table as referenced primary key.4. Can not reference a remote table or synonym.

Examples:

1. Explicit reference to a PRIMARY KEY column

CREATE TABLE accounts (account NUMBER(10) ,CONSTRAINT borrower FOREIGN KEY (account)

REFERENCES customer (account), ...);

2. Implicit reference to a PRIMARY KEY column

CREATE TABLE accounts ( account NUMBER(10), CONSTRAINT borrower FOREIGN KEY (account)

REFERENCES customer, ...);

22. What is data integrity? What are the types of integrity?

1. A mechanism used by the RDBMS to prevent invalid data entry into the base tables of the database.2. Defined on tables so conditions remain true regardless of method of data entry or type of transactions.

The following are the type of integrity

* Entity integrity * Referential Integrity

* General Business rules

23. What is a Referential Integrity?

1. Enforces master/detail relationship between tables based on keys.

* Foreign key* Update Delete restricts action* Delete Cascade action

24. What are different data types?

The following are the different data types available in Oracle1. Internal Data types2. Composite Data types

Internal Data types 1. Character Datatype2. Date Datatype3. Row and long row data types4. Rowid Datatype

Composite Data types

1. Table Data type2. Record Data type

25. What is VARCHAR2? How is it different CHAR?

The Varchar2 datatype specifies a variable length character string. When you create a varchar2 column, you can supply the maximum number of bytes of data that it can hold. Oracle Subsequently stores each value in the column exactly as you specify. If you try to insert a value that exceeds this length, Oracle returns an error.

The Char datatype length is 1byte. The maximum size of the Char datatype is 255. Oracle compares Char values using the blank-padded comparison semantics. If you insert a value that is shorter than the column length, Oracle blank-pads the value to the column length.

26. What is datatype mixing?

There are two data types %TYPE and %ROWTYPE. The first one declares a variable to be of the data type of the column of the table to which it is referring.

For example, if you declare a variable like this:

my_empno emp.empno%TYPE

then, my_empno will have the data type of the empno column of the table emp.

Similarly if you declare the variable like this:

my_emprec emp%ROWTYPE

then, my_emprec will have the data type of all the fields of the emp table.

For example. Suppose employee table is like this: empno number(2),

empname varchar2(10), Sal number (10,2).

Then my_emprec will be of a data type whose first 2 positions will be of number data type, the next 10 will be of varchar2 data type while the last 10 will be of data type number.

One can refer to the individual fields of this record variable as my_emprec.empno, my_emprec.empname, my_emprec.sal.

27. What is NULL?

A data field without any value in it is called a null value.

A Null can arise in the following situation * Where a value is unknown. * Where a value is not meaningful (i.e.) in column representing commission for a row that does not represent salesman.

28. What is a sequence?

A sequence is a database object from which multiple users may generateunique integers.

29. What are pseudo-columns in ORACLE?

The columns that are not part of the table are called as pseudo columns. 30. What is like operator? How is it different from IN operator?

The type of operator that is used in character string comparisons with pattern matching. Like operator is used to match a portion of the one character string to another whereas IN operator performs equality condition between two strings.

31. What is Single Row numbers Functions?

The type of function that will return value after every row is being processed.

Following are some of the row number functions.

Function Name Purpose

1. ABS (n) returns the absolute value of a number

2. Floor (n) returns the largest integer valueequal or less than n.

3. Mod (m, n) returns the remainder of m divided by n.

4. Power (m, n) returns m raised to the n power.

5. Round (n) returns n rounded to m placesright of a decimal point.

6. Sqrt (x) returns the sqrt value of x.

7. Trunk (n, m) Returns n truncated to m decimalplaces.

32. What are single row character functions? The function that processes at value of data, which is of character datatype, and returns a character datatype after every row is being processed are termed as single row character functions.

Function Name Purpose.

1. Char (n) returns the character havingan ASCII value.

2. Initcap (n) returns character with firstletter of each argument inUPPERCASE.

3. Lower (n) returns characters withall the letters forced tolower case.

4. ltrim(n) Removes the spaces towardsthe left of the string.

5. upper(n) Returns characters withall the letters forced toupper case.

33. What are Conversion Functions?

The functions used to convert a value from one datatype to anotherare being termed as conversion functions.

Function Name Purpose

To_char (n, (fmt)) converts a value of number datatypeto a value of character datatype.

To_number (n) converts a character value into a number.

Rowidtochar (n) converts rowid values to character datatype.the result of this conversion is always18 character long.

34. What are Date functions?

Functions that operate on Oracle Dates are termed as Date functions.

All date functions return a value of date datatype except the \function months_between returns a numeric value.

Function Purpose

ADD_MONTHS (d, n) returns the date 'd' plus n months.n must be an integer.n can be positive or negative.

LAST_DAY (d) returns the date of the last dayof the month containing the date 'd'.

NEXT_DAY (d, char) returns date of first day of weeknamed after char that is later thand, char must be a valid day of theweek.

MONTHS_BETWEEN (d, e) returns no of months between datesd & e.

35. What is NEW_TIME function?

SYNTAX: New_time (d, a, b) New_time function returns date and time in a time zone b and time in time zone. a and b are character expressions.

Following are the some of the character expressions:

Character expression Description

AST Atlantic Stand or daylight timeBST, BDT Burning stand or daylight timeGMT Greenwich Mean Time.PST, PDT Pacific Standard Time.YST, YDT Yukon standard or daylight time.

36. What is Convert function?

Convert function converts two different implementations of thesame character set .

For instance: from DEC 8 bit multi-lingual characters to HP 8 bitMulti-lingual character set.

Following are the character sets

US7ASCII - US7bit ASCII character setWE8DEC - Western European 8 bit ASCII setWE8HP - HP's Western European 8 bit ASCII setF7DEC - DEC's French 7-bit ASCII set

Convert (char [destination], [source])

37. What is a translate function?

The function that returns a character after replacing all occurrencesof the character specified with the corresponding character is calledas translate function.

E.g. TRANSLATE ('Hello','l','L') gives you HeLLo

38. What is a soundex function?

Soundex is a function that returns a character string representingthe sound of the words in char. This function returns a phoneticrepresentation of each word and allows you to compare wordsthat are spelled differently but sound alike.

Soundex (char);

39. What is a replace function?

Replace function returns character with every occurrence of thesearch string replaced with the replacement string. If the replacementstring is not supplied, all occurrences of search_string are beingremoved. Replace allows you to substitute one string from another.

40. What is a Floor function?

Floor Function returns the largest integer equal to or than n

Syntax: floor (n);

41. What is INITCAP Function?

The initcap function returns char,with first letter of each word in uppercase, all other letters in lowercase. A word is delimited by white space

42. What is ASCII Function?

The ASCII function returns the collating sequence of the first character of lchar. There is no corresponding EBCDIC function.On EBCDIC systems, the ASCII function will return EBCDIC collatingsequence values.

43. What is a Decode Function?

The Decode function is used to compare an expression to each searchvalue and returns the result if expr equals the search value.

E.g.: Decode (expr, search1, result1, [search2, result2], [default]);

44. What is Greatest Function?

The Greatest function returns the greatest of a list of values. All expr after the first are converted to the datatype of the first beforecomparison is done.

45. What are Format models?

Format models are used to affect how column values are displayed whena format retrieved with a select command. Format modelsdo not affect the actual internal representation of the column.

46. Give 5 examples for DATE, Number function?

Examples for Number Function:

1. Select abs (-15) "Absolute:" from dual2. Select mod (7,5) "Modula" from dual3. Select round (1235.85,1) from dual4. Select power (2,3) from dual5. Select floor (7.5) "Floor" from dual

Examples for Date Function

1. Select sysdate from dual2. Select sysdate-to_date (23-Sep-93) from dual3. Select sysdate + 90 from dual4. Select sysdate -90 from dual5. Select next_day (sysdate,"Friday") from dual

47. What is an expression?

An expression is a group of value and operators which may be evaluated a single values.

48. What are the types of expression?

The different types of expressions are

1. Logical expression2. Compound expression3. Arithmetic expression4. Negating expression.

49. What is a synonym?

The synonym is a user-defined object that is used to define an alias name for the user defined objects like table view etc.

50. What is a condition?

A Condition could be said to be of the logical datatype that evaluatesthe expression to a True or False value.

51. What are the 7 forms of condition?

There are totally 7 forms of condition1. A comparison with expression or subquery results.2. A comparison with any or all members in a list or a subquery3. A test for membership in a list or a subquery4. A test for inclusion in a range 5. A test for nulls.6. A test for existence of rows in a subquery7. A test involving pattern matching8. A combination of other conditions

51. What are cursors?

Oracle uses work areas called private SQL areas to execute SQL statements and store processing information. This private SQL work area is known as cursors.

52. What are explicit cursors?

Cursors that are defined for performing a multiple row select are knownas explicit cursors.

Implicit cursors are the type of cursors that is implicitly openedby the Oracle itself whenever you perform any DML statements likeUpdate, delete, insert or select into statements.

53. What is a PL/SQL?

PL/SQL is a transaction processing language that offers proceduralsolutions.

54.What is an embedded SQL?

All the SQL statements written in a Host language are knownas Embedded SQL statements.

56. What are the different conditional constructs of PL/SQL?

The statements that are useful to have a control over the setof the statements being executed as a single unit are called asconditional constructs.

The following are the different type of conditional constructsof PL/SQL

1. if <condition> then elsif<condition> then end if

2. While <condition> loop end loop

3. loop exit when<conditon> end loop

4. for <var> in range1..range2 loop end loop

5. for i in <query/cursor identifier> loop end loop

57. How is an array defined in PL/SQL?

Typedef <identifier> table of <datatype>Index by binary_integer;

58. How to define a variable in PL/SQL?

Variablename datatype<size> <not null> <: = value>

59. How to define a cursor in PL/SQL?

Cursor variable is <query>

60. What are exceptions?

The block where the statements are being defined to handle internally and userdefined PL/SQL errors.

61. What are the systems exceptions?

When an Oracle error is internally encountered PL/SQL blockraises an error by itself. Such errors are called as internalor system defined exception. Following are some of the internal exceptions:1. Zero_divide, 2. No_data_found 3. Value_error 4. Too_many_rows

62. How to define our own exceptions in PL/SQL?

Define a PL/SQL variable as an exception in the variable declaration section.

In order to invoke the variable that is an exception type use the raise statement.

Declare a exception; Begin statements.... -----if x > y then raise a; end if;exception when a then statements, rollback; when others then commit;end;

63. How is the performance of Oracle improved by PL/SQL in Oracle?

Without PL/SQL the ORACLE RDBMS must process SQL statements one at a time, Each SQL statement results in another call to RDBMS and higher performance overhead. This overhead can be significant when you are issuing many statements in a network environment.With the PL/SQL all the SQL statements can be sent to RDBMS at one time.

This reduces the I/O operations. With PL/SQL a tool like Forms can doall data calculations quickly and efficiently without calling onthe RDBMS .

64. What is SCHEMA?

A SCHEMA is a logical collection of related items of tables and Views.

65. What are profiles?

A Profile is a file that contains information about the areas that a user can access.

66. What are roles?

A role is a collection of related privileges that an administrator can grant collectively to database users.

67. How can we alter a user's password in ORACLE?

Inorder to Alter the password of the user we have to use the following statement:

ALTER USER user_name identified by passwd

E.g.: Alter user sam identified by Paul

68. What is a tablespace in Oracle?

A tablespace is a partition or logical area of storage in a database that directly corresponds to one or more physical data files.

69. What is an extent?

An extent is nothing more that a number of contiguous blocks that ORACLE-7 allocates for an object when more space is necessary for the object data.

70. What are PCTFREE and PCTUSED parameters?

PCTFREE: - PCTFREE controls how much of the space in a block is reserved for statements that update existing rows in the object.PCTUSED: - PCTUSED is a percentage of used space in a block that triggers the database to return to the table's free space list.

71. What is a block in Oracle?

The Place where the data related to Oracle are stored physically in an Operating System is known as block.

72. What is Client-server architecture?

A client/server system has three distinct components Focusing on a specific job A database server A client application and a network.

A server (or back end) focuses on efficiently managing its resource Such as database information. The server's primary job is to manage its resource optimally among multiple clients that concurrently request the server for the same resource.

Database servers concentrate on tasks such as

* Managing a single database of information among many concurrent users.* Controlling database access and other security requirements.* Protecting database information with backup and recovery features.* Centrally enforces global data integrity rules across all Client applications.

A client application ("the front end") is the part of the system that users employ to interact with data. The client applications in a client/server database system focus on jobs such as

* Presenting an interface a user can interact with to accomplish work.* Managing presentation logic such as popup lists on a data entry form or bar graphs in a graphical data presentation tool.

* Performing application logic, such as calculating fields in a dataentry form.* Validating data entry.* Requesting and receiving information from a database server.

A network and communication software is the vehicle that transmitdata between the clients and the server in a system. Both the clientsand the server run communication software that allows them to talk across a network.

Types of Client Server Architecture:

1. Dedicated Client Server Architecture2. Multi-threaded Client Server Architecture3. Single- Task Client Server Architecture

Dedicated Server: Connects the Client Directly to the dedicated server

Multi-Threaded Server: It is a type of architecture that is a combination of dispatcher, listener and front-end server process to serve the requests of many clients with minimal process overhead on the database server.

Single-Task server: In host-based database server system a useremploys a dumb terminal or terminal emulator to establish a sessionon the host computer and run the client database application.

73. What is a segment in Oracle? Explain the different types?

The places where the data are stored in the allotted tablespace are called as segments. The data may be a table or index data required by DBMS to operate. Segments are the next logical level of a storage tablespace.

There are basically 5 types of segments* Data segment: Contains all the data of each table* Index segment: Contains all the index data for one or more indexesCreated for a table.

* Rollback segment: Contains the recorded actions, which should be undone under certain circumstances like* Transaction rollback* Read consistency* Temporary segment: Whenever a processing occurs Oracle often requires temporary workspace for intermediate stages of statement processing. These areas are known as temporary segments.

* Bootstrap segment: Contains information of the data dictionary definition for the tables to be loaded whenever a database is opened.

74. What is the use of Rollback segment?

It is a portion of a database that records the information about the actions that should be undone under certain circumstances like

* Transaction Rollback* Read consistency

75. What is read-consistency in Oracle?

Read consistency in Oracle is a process that ignores the changes by others in a table whenever a table is queried. Read consistency in Oracle is achieved by a statementSET TRANSACTION READ ONLY

76. What is SGA?

SGA is System Global Area.

The library cache and dictionary cache makes up the shared pool. The shared pool combined with buffer-cache make up the System Global Area.Library Cache: - It stores the SQL Statements and PL/SQL Procedures.Dictionary Cache: - Holds dictionary information in memory.Buffer and Cache: - the place where the data related to recently requested transaction is stored.

77. What is Back Ground Process?

The Process of server is being classified into two processes namely Foreground and Background.

Foreground handles the request from client processes while background handle other specific row of the database server like writing data to data and transaction Log Files.

78. System Userid?

Whenever you create a database an Userid is automatically created related with database administration connections. This account/userid is called System Userid.

79. SYS Userid?

It is a special account through which DBA can execute special database administration connections. SYS is the owner of database's data dictionary table.

80. Data Dictionary?

It provides the details on the database objects such as columns, views Etc., the oracle users, the privileges and the rights of users over different objects.

81. SQL*DBA?

SQL*DBA is a utility through which you can manage a database system effectively.

82. ORACLE ADMINISTRATOR?

The person who takes care of monitoring the entering performances of the database system is called, as an Oracle Administrator.Oracle Administrator is the main person who takes care of assigning the set of to act as DBA for monitoring certain jobs like 1. Creating primary database storage structure. 2. Monitoring database performance and efficiency. 3. Backing up and restoring. 4. Manipulating the physical location of the database.TO CREATE DATABASE: 1. Determining appropriate values for the file limit parameters of the create database command. Parameters Max data files: Determines the maximum number of data files that can ever be allocated for the database Max Log Files: Determines the maximum number of log groups for the database. Max Log Members: Maximum number of members for each log group.

84. What are database files? The physical files of Oracle are known as database files.

85. What is a Log File?

The files that contains information about the information of recovery of oracle database at the event of a SYSTEM CRASH or a MEDIA Failure.

86. What is an Init file?

Init files are known as Initialization Parameter files. Init files are used for setting the parameters * For an Oracle instance* For Log files

87. What is a control file? What is its significance?

A control is a small binary file. It contains the entire system executable code named as ORACLE.DCF.

A control file always consists of the following1: Name of the database2: Log files3: Database creation

88. What does an UPDATE statement does? To update rows in a table.

89. What does a Delete statement does? To remove the rows from the table.

90. What does an insert statement do?

To insert new rows into a database.

91. What does a Select statement do? To query data from tables in a database 92. How to create a table using selects and inserts statements?

Using Select statement:

Create table tablename as<Query >

Using insert statement we cannot create a table but can only appendthe data into the table

Using Insert statement:

Insert into tablename<Query>

93. How to delete duplicate rows in a table?

Delete from tablename where rowid not in(Select min (rowid) from tablename group by column1, column2...)

94. What is an instance?

An Oracle instance is a mechanism that provides the mechanism for processing and controlling the database.

95. What is startup and shutdown?

Startup is a process making the Oracle Database to be accessed by all the usersThere are three phases to database startup1. Start a new instance for the database2. Mount the database to the instance3. Opening the mounted database

Shutdown is a process making the Oracle Database unavailable for allthe users.

There are three phases to database shutdown

1. Close database

2. Dismount the database from the instance

3. Terminate the instance.

96. What is mounting of database?

97. What is a two-phase commit?

98. What are snap-shots?

A Snapshot is a stable that contains the results of query Of one or more tables or views, often located on a remote database.

99. What are triggers and stored Procedures?

A procedure is a group of PL/SQL statement that you call by a name. Compiled version of procedure that is stored in a database are known as Stored Procedures.A database trigger is a stored procedure that is associated with a table.Oracle automatically fires or executes when a triggering statement is issued.

100. What are Packages?

A package is an encapsulated collection of related program objects stored together in the database.

101. What is SQL*Forms3.0? Is it a Client or a server?

Sql*Forms is a general-purpose tool for developing and executing forms based interactive applications. The component of this tool is speciallydesigned for application developers and programmers and it is used for the following tasks :

* Define transactions that combine data from multiple tables into a single form.* Customize all aspects of an application definition using std-fill-in- interface to enhance the productivity and reduce learning time.

Sql*Forms3.0 is a Client.

102. What are Packaged Procedures?

A packaged procedure is a built in PL/SQL procedure that is available in all forms.

Using packaged procedure we can build triggers to perform the following Tasks to* Reduce the amount of repetitive data entry.* Control the flow of application* Ensuring the operators always follow sequence of actions whenthey use a form.

103. What are different types of triggers?

The following are the different type of triggers they are

1. Key-triggers2. Navigational Triggers.3. Transactional Triggers.4. Query-based Triggers5. Validation Triggers6. Message - Error handling Triggers.

104. What is the difference between the restricted and Un-Restricted Packaged Procedure?

Any packaged procedure that does not interfere with the basic functionof SQL*Forms is an unrestricted packaged procedure. The Un-restrictedPackaged procedure can be used in all types of triggers.

Any packaged procedure that affects basic SQL*FORMS function is a restricted packaged procedure. Restricted packaged procedure can be used only in key-triggers and user-named triggers.

105. What is a system variable?

A System variable is a SQL*Forms variable that keeps track of some internal process of SQL*Forms in state. The system variable helps us to control the way an application behaves. SQL*Forms maintains the value of a system on a performance basis. That is the values of all the system variables correspond only to the current form.

106. What are Global Variables?

A Global variable is a SQL*Form variable that is active in any trigger within a form and is active throughout SQL*Form (Run-Form) session. The variable stores string value upto 255 characters.

107. What are the different types of objects in SQL*Forms?

A SQL*Form application is made up of objects. These objects contain allthe information that is needed and produce the SQL*Forms application.

Following are the objects of the SQL*Forms:

1. Form2. Block3. Fields4. Pages5. Triggers6. Form-Level-Procedures.

108. What are Pages?

Pages are collection of display information such as constant text and graphics. All fields are displayed in a page.

109. What are a Block and its types? Explain the different types of blocks?

Block is an object of Forms that describes section of a form or a subsection of a Form and serve as the basis of default database interface.

Types of Blocks:

1. Control Block: Control block is not associated with any table in thedatabase. It is made up of fields that are base table fields, such as temporary data fields.

2. Detail Block: Detail Block is associated with a master block in Master-detail relationship. The detail block displays detail records associated with master records in a block.

3. Master-Block: A master block is associated with a master-detail relationship. The master block display master records associated with detail records in the detail block.

4. Multi-record Block: A multi-record block can display more than one record at a time.

5. Non-enterable Block: A non-enterable block consists of all non-enterable fields.

6. Single-record Block: A single record block can display only one record at a time.

110. What is a Screen Painter?

This is a SQL Forms "work area" where you can modify the layout of forms. The screen painter displays one page area at a time.

111. What are the different field types?

The different types of fields in SQL*Forms are 1. Base - table field

2. Control-field3. Enterable-field4. Hidden-field5. Look-up field6. Non-enterable field7. Scrolled - field

112.What is page Zero?

The place where the hidden fields are being placed in an application

113. What does Message procedure do?

The Message procedure displays specified text on the message line.

114. What does Name_in function do?

The Name_in packaged function returns the contents of the variable to which you apply it. The returned value is in form of a string.

115. What does CLEAR_EOL procedure do?

Clear_Eol clears the current field's value from the current cursor position to the end of the line or field.

116. What does On-Error trigger do?

The On-error trigger fires whenever SQL*Forms would normally cause an error message to display. The actions of an On-Error triggers is used for the following purposes:

* Trap and recover an error.* Replace a standard error message with a customized message.

117. What does copy procedure do?

The Copy procedure writes a value into a field. Copy exists specifically to write a value into that is referenced through NAME_IN packaged function.

118. What is the Arraysize parameter?

The Array-Size parameter is a block-characteristic that specifies the Maximum number of records that SQL Forms (Run-Form) can fetch from the database at one time.

119. What does Go_Block packaged procedures do?

The Go_Block packaged procedure navigates to the indicated Block.If the target is non-enterable an error occurs.

120. What does ANCHOR_VIEW procedure do?

Anchor_view moves a view of a page to a new location on the screen. This procedure effectively changes where on the screen the operator sees the view.

121. How to call a form from inside a form?

Inorder to call a form from inside a form we have to use the CALL packaged-procedure.Inorder to call a form from inside a form the packaged procedure Call is used. Syntax: CALL (Formname).

When call runs an indicated form while keeping the parent form active.SQL*Forms runs the called form with the same SQL*Forms options as theparent form.

122. How to send parameters to another form?

Inorder to send parameters across the forms we use the global variables.

123. How to give automatic hint text for fields?

Inorder to give automatic hint text for fields, In the field definition screen of the fields we are having an option called Hint value. Inorder to activate this option in the Select attribute section invoke the option called Automatic Hint.

124. How to see key map sequences?

Inorder to see key map sequences we have to press the SHOW KEY screen key function.

125. What is SYNCHRONIZE procedure does?

The synchronize procedure synchronizes the terminal screen with the internal state of form, that is synchronize updates the screen display to reflect the information that SQL*Forms has in its internal representation of the screen.

126. What is EXECUTE_QUERY procedure?

The Execute_query procedure flushes the current block, opens a query and fetches a number of selected records. If there are changes to commit, SQL*Forms prompts the operator to commit them during the execute_qury event.

127. How to customize system message in SQL*Forms?

Inorder to customize the system messages the On-Message trigger is used.

128. How to define the fields in WYSIWYG Format?

129. What is an On-Insert trigger? How is it different from Pre-inserttrigger?

An On-insert trigger replaces the default SQL*Forms processing for handling inserted records during transaction posting. It fires once for each rows that is marked for insertion into the database. An On-insert Trigger fires during the Post and Commit Transactions event. Specifically it fires after the Pre-insert trigger and before the

Post-insert trigger.

130. What is the difference between a Trigger and a Procedure?

Procedures can take in arguments where as Triggers cannot take in arguments.

131. How to call a stored procedure from inside a form?

To call a Stored Procedure inside a form

Trigger Text:

Procdurename<paramaters>

132. What are V2 Triggers?

V2 Triggers are the types of Triggers in which we can perform only a simple query. And we cannot write a PL/SQL block.

133. How to rename a Form?

To rename a form select the rename option in the Action Menu. Then give the form name. Press Accept. In the next field give the new name. Press Accept to Execute.

134. What is a Pop -up page? How to define one?

Pop-Up Pages: -Pop-Up page is a SQL*Forms object which overlays on an area of the current displayed page in response to some event or for user call. To define a Pop-Up page use the page definition form which is in the Image-Modify option. In that form put an X in the Pop-Up field to make the current page as Pop-Up.

135. What is a Group in SQL * REPORTWRITER?

Group in ReportWriter: -

Group is a collection of fields, or single field. Usually by default a group will bare the field, which are references by a single query. But we can change from single query group -multi groups.

136. How do you define a Parent-child relationship in ReportWriter? Parent - Child Relation: -

To define a Parent-Child relationship first we need more that one Query. We should first enter the Parent Query and then the Child Query. In the Child Query Form we should give the Parent Query Name in the desired position and the common columns in both queries.

137. What is a Rowcount function in ReportWriter?

It is a field level function that is used for generation of automatic row numbers related to database column that does not have null values.

138. How do you define a matrix report?

Matrix Report: -

Matrix Report is a Report that consists of Two Parent Queries and one Child Query.

Procedure for Defining a Matrix Report:

1. Define Two Parent Queries.

2. Define a Child Query. In the Definition screen specific which column of the child is to be related to the Query1 and to Query2.

3. After defining the queries in the Query option, In theGroup option

Place All the Groups in the option called MatrixGroupDefine the Print Direction for Query1 as downDefine the Print Direction for Query2 as acrossDefine the Print Direction for Child Query as cross tab

139. How do you execute a report from within a form?

Use the following command to run a report from the FORM.

Host ('runrep <rep_name> term<terminal_type> userid=<userid/passwd>);

140. What are exp and imp utilities? Export & Import: -

Export utility is to write data from database to operating system files called Export Files. An export does this by changing the data and table structures in to ASCII or EBCDIC codes.

Import is a utility with which we can write the data from Export file to database. Export Files can be only read by Import.

RIGHTS RESERVED BY DEEPAK SAMUEL K J

Questions and Answers--------------------------------- FORMS 4.5 *************************

1. What are the different modules of forms 4.5?

Forms, menus, library.

2. What are the differences between forms 4.5 and forms 3? Form 4.5: GUI Forms 3.0: Cui database objects,forms_ddl.

3. What is the maximum limit for creating blocks and canvas in forms 4.5? Unlimited Forms 3.0: triggers (75) Forms 4.5: triggers (121)

4. In a multi record block can we have an item displayed once?

5. After creation of block can we have create a button palette? No

6. What are the differences between form4.5 and forms 3.0 with regards to master detail relationship explain all the properties of master detail in detail? On clear details, On populate details in forms 3.0 for 1 child only one parent but not so in forms4.5

7. What are the difference types of triggers that will be created for master deletes properties such as isolated, non isolated, cascading? For non-isolated

1) On-clear-details 2) On-populate-details 3) On-check-delete-master (checks for existence for child record)

For isolated

1) On-clear-details 2) On-populate-details

For cascading

1) On-clear-details 2) On-populate-details 3) Pre-delete

Coordination properties a) Deferred by default false Autoquery by default false If deferred true, autoquery true->defered with autoquery Here the child block waits for navigation once navigated to, Automatically corresponding child rows will be displayed. b) Deferred true, autoquery false->child block needs navigation as well as explicit execute query. c) Deferred false, autoquery true ->invalid as it has the same effect as that of first (deferred false, autoquery false) Prevent masterless operation ->if true without going to the master, child rows can't be manipulated.prevents any manipulation without master record.

8. What is the difference between creating a master detail new block window and creating relations after creation of the blocks?

9. How to set relation properties dynamically? Set_relation_property

10.How many types of items are there in form 4.5? 9

11.What are the different types of list items and the triggers associated with them? Pop_list, Combo box, T list When list changed, When list activated

12.Can we change a color of push button? No

13.What is the significance of other values in property of check box? User can give a value, which is not in checked or unchecked Not allowed (entry of other values)

13 what are the different types customs items and the triggers associated with them? OLE, VBX.Trigger: When custom item event

14 What is the radio group? Is a dummy radio button necessary? What is the associated trigger? How to disable a radio button dynamically? Set radio button property (block name.radio group name, button name , enabled,property false) When radio changed

15.For, which type of items mouse navigable property, is applicable? Check box, list box, image item, push button, radio buttons

16 What is the difference between text items and display item? Text item can be navigable, display item can not be navigated.

17.What is difference between single line text items and multi line text items? 18.What are the types of items that are always control items? push button(not available in the base table items.Hence they are control items)

19.How to invoke lov dynamically? Show lov, list values

20.What do lov for validation do when it is set true?If other values other than current listed values are entered, it will not be accepted till a correct value is entered the list will be invoked.

21.What are the values that a where clause can reference in lov? Block.item name, parameter, global variable

22 What is the difference between list values and show lov? For list values we have to attach the lov to item For show lov it is not needed Show lov return a Boolean value depending upon that an operation can be taken

23.What is a record group? Different types record group? How to create query record group dynamically? Static, query, non query Design time->static, query only For run time you can have all the three

24 How many no. of columns that a record group can have? Memory should not exceed 64k

25 Give an live example where you can use non query record group? Multi record validation

26 what does populate group return when a query succeeds?Arg will be created dynamically it returns a number which must stored in the variable of data type number.

27.How to change a lov from one record group to another? Set lov property, get lov property.

28.What are the different types of canvases? Stacked, content, htb, Vtb

29 Explain raise on entry property? In a content canvas a stacked canvas. Content property: raise on entry - >true when navigation from the pop up block is returned back to content block,pop should be disappear and this content block should appear .

30.What are the content view? Base table view

31.What are differences between show_view and replace_content_view?

32.What are the different types of window? Application window, secondary window Styles->dialog, document Depending upon modal property if modal = true modal window if modal property false modal less window Console window-> status, message window appears at the bottom of the screen.

33. How to display window programmatically? Set_window_property (window name, visible, property_true) Show_window (window name)

34. To which types of window remove an exit property is meaningful? For modal less window

35.To, which type of window the scroll bar, do not apply? Modal window

36 How to scroll a window dynamically?

Set_window_property (window name, x, y)

37 How to resize a window? Resize_window (window name, width, height)

38 How to increase the size the window dynamically? Set_window_property (forms_mdi_window, window_status, maximize)39 What are the window event triggers? When window activated, when-window-resized When-window-deactivated, when-window-closed

40 What is the console window? on what window it will be displayed? Can we change the console window at run time? Console window is the root window. No dynamic assignment to root Window.where message line, status line appearing

41 Define a) property class b) Visual attributes what are the differences between property class and visual attributes? 1.if property class, visual attributes are attached to a particular item or objects, visual attributes take precedence over property Class set_block_property(block name,current_record_attribute,'va name') Trigger can be written on property class dynamically VA can be attached to an object but PC can not be attached

42. How to change a VA dynamically? set_block_property,set_item_property

43. If i change a property in the field, which is, attached to a VA what will happen? Changes from user_defined to customs

44. What is library? PL SQL codes can be put and hence can be attached to menus forms library itself.

45. What is difference between program units and attach library? It is read only (AL) as it depends on the library all manipulations Can be done

46.What types of reference can i use in library? name in(indirect reference)

47. What are the different types of menus? pull down,bar menu,full screen

48 How to attach menu in the form? Form properties

49. How to replace menus dynamically? replace menu(menu name)

50.What are all the different types of menu items? Plain, radio, check, magic, separator

51.In which platform background menu are supported? Full screen

52 what are the different types of codes we write in menus? menu_startup code,menu item code

53 what are the ways of references you will be using in writing a menu code?

54 What is an alert? How to change an alert message dynamically? What types of window is an alert? What is the max no of char? Response window, modal window, 200,set_alert_property (an, alert_message_ text,'message');

55 how many triggers are available in forms 4.5->12156 what is freeze and un freeze? To see property of more than one object at a time

57 what are the diff bet global vars and para? Global ->255k para->2 Global-> char para->char, num, data, rg, date

58 what are the objects that i can't create in the objnav? Boiler plate text, bitmap, image, and timer.

59 what do you mean by copying and referencing? Copying ->no updating in the main Refer-> updating takes

60 when you copy a referenced object what will be a resultant object? Referenced object

61 how to reuse plsql codes? By either put it in lib or property class triggers

62 how to use ddl stmts. in forms 4.5? Forms_ddl ();

63 discuss briefly about multi forms functionality? Restricted procedures->open form, new Unrestricted procedures->call form

64 how many system vars are there in forms 4.5? 42

65 what does the sys_mouse_button_pressed sys var do? Will return the button value (left or right)

66 what is sys variable that is used to determine the current mode? System.mode types: normal, query, enter query (always within quotes and caps)

67 what are the various categories of triggers explain?

68 what are the diff type of editors? Systemdefined (notepad), userdefined, default.

69 what is diff between edit_text_item and show_editor? First one must be attached; second there is no need

70 how many built-in functions and procedures available in forms 4.5? 150.

71 what are the triggers that are valid in enter query mode? Key-triggers, on-error, on-message, in when triggers except When-database-record, when-val-item, when-val-rec

72 what does the property called secure? What will happen when it is set true? For passwords settings at item level

73 what do you mean by ownership, visual views?74 how to change default where and order by clause dynamically? 1.set_block_property (blname, default_where,'empno >1000'); 2.set_block_property (blname, order_by,'itemorcolumn');

75 how to modify default navigation sequence? In property of any item, navigation’s property's. If at block nextnavigation block property.

76 what is all the property of items that you can validate without Writing triggers? default value,range,data typpe,required,primary key etc.,

77 explain detail about debugger?

78 if you are using procedures created in libs, database, formlevel which will advantageous? Libs

79 compare post-fetch trigger post-query trigger, post-forms-commit, Post-database-commit, pre-query pre-select

80 a) if I have a pk in the table and while creating a block and if I On constraint option what trigger will be created? When-validate-item

b) If it’s a composite pk what trigger is generated? When-validate-record

c) If I have pk, fk in table and if I on the constraint option What trigger will be created? When-remove-record

REPORTS 2.5

*****************************81 what are the different types styles of reports? Matrix, tabular, forms, form letter, mast-debt, and mail.

82 how many groups are required for a matrix report? 3

83 what are the steps involved in creating a pagewise summary column? 84 explain default layout, layouteditor

85 what is an external query?

86 through which object you are establishing link between groups? Datalink

87 what is formula column, placeholder column?

88 what is anchor?

89 what is a parameter? Different types of parameters? Trigger associated with them? Lexical, bind, system

90 can we use ddl statements in reports 2.5?

91 what is a drill down report?

92 trigger associated with push button? When-button-pressed

93 what are the diff types of report triggers? List the sequence in which they fire?

94 can I use dml stmts. in format triggers?

95 what is the significance of group filter trigger?

96 how to control the number of records retrieved?

97 can we refer to column values in reports?

98 in the table I have a value for ename as Allen but I want to Print it as **** in the preview screen printer is it possible if so how? Set_item_property ('itna', secure, property_true);

99 I want three records to displayed in a page?

100 how to integrate reports 2.5 with forms 4.5 how to pass parameters from forms to reports? Run_product (); ***********************************************************************

ORACLE NON-DBA FAQ (Frequently Asked Questions)

----------------------------------------------- TABLE OF CONTENTS =================

1. GENERAL QUESTIONS 1.1. What is Oracle? 1.2. What are the advantages of Oracle? 1.3. What are potential disadvantages of Oracle? 1.4. What is SQL? 1.5. What is PL/SQL? 1.6. What is Procedural Option? 1.7. What products are available from Oracle? 1.8. What Public Domain interfaces are there? 1.9. What third party interfaces are available? 1.10. How portable is Oracle applications to other RDBMS? 1.11. What Query Optimizers are there? 1.12. Is there an anonymous FTP site for Oracle stuff? 1.13. What mail lists are there? 1.14. What bulletin boards are there? 1.15. What news groups are there? 1.16. How does Oracle compare to...? 2. SQL QUESTIONS 2.1. How can I avoid a divide by zero error? 2.2. Can I update tables from other tables? 2.3. Can I remove duplicate rows? 2.4. Can I update using a view? 2.5. Are views automatically updated when I update base tables? 2.6. Should we use complex views that cruel performance? 2.7. Can I implement tree-structured queries? 2.8. How can I get information on the row based on group information?

2.9. How can I get a name for a temporary table that will not clash? 2.10. How can I find out about what tables, columns and indices there are ? 2.11. Is there a formatter for SQL statements? 2.12. What is the DUAL table? 2.13. What is the difference between CHAR and VARCHAR? 2.14. What is ROWNUM good for? 2.15. How do I get a top ten? 2.16. How can I control the rollback segment I use? 2.17. How can I order a union? 2.18. How can I rename a column? 2.19. Who are SCOTT/TIGER, SYSTEM and SYS? 2.20. Who do various access methods compare? 2.21. What are clusters? 2.22. How can I update a big table without blowing rollback segments?

2.23. Why don't I get records for the date I want?

3. SQL*PLUS QUESTIONS 3.1. How can I control the startup configuration of SQL*Plus? 3.2. Can I get a column value into a substitution variable? 3.3. How can I change the (hated default) editor to my favorite? 3.4. What is the difference between & and &&? 3.5. What is the difference between "host" and "!”? 3.6. Why can't I use a table name in a substitution variable? 3.7. How can I see all of a LONG?

3.8. How can I force a column to begin on the left of the page? 3.9. Can I alias SQL commands?

3.10. Can I escape significant punctuation marks?

4. SQL*FORMS 3 QUESTIONS 4.1. How can I get a list of values from a hard coded list? 4.2. How can I get find to look at description with list of values? 4.3. Can I edit SQL*Forms code with my text editor? 4.4. Can I edit SQL*Forms code by updating the database? 4.5. Why can't I see data in a control field? 4.6. Why is my terminal scrambled in a user exit? 4.7. What happens to LONGs? 4.8. What are user-written form level functions? 4.9. How can I use regular expressions for field validation? 4.10. What is a user-exit?

4.11. How can I call a popup window for field validation?

5. SQL*FORMS 4 QUESTIONS 5.1. What new features can be expected in forms 4 generator from CASE ?

5.2. What new features can be expected in forms 4?

6. PRO*C QUESTIONS 6.1. Why are my C variables overwritten? 6.2. Can I use C preprocessor definitions for VARCHAR size? 6.3. What can I do about "line too long" errors with version control? 6.4. Why do my compiles crash or weird things happen?

6.6. How do I use OPS$login?

7. CASE QUESTIONS7.1. Can CASE generate forms with owner propounded to table names?7.2. Can CASE generate V7 databases?

8. UNIX QUESTIONS8.1. Can I create a compressed export on the fly without needing to have the space for both the export file and the compressed file?

8.2. How can I prevent trailing spaces in a spooled report? 8.3. How can I get an environmental variable into SQL*Plus variables? 8.4. Can I pipe stuff through SQL*Plus? 8.5. Why does Pro*C compiles or programs crash on my Sun? 8.6. How can I find a lost Oracle export file? 8.7 How can I tell make about SQL*Forms?

9. MISC QUESTIONS9.1. How can I alter table storage parameters from an export file?

9.2. What makes the best Oracle server for a network? 9.3. How can I implement version control? 9.4. What books are available about Oracle?

1. GENERAL QUESTIONS 1.1. What is Oracle? Oracle is a trademark of Oracle Corporation and in common usage refers to the database engine (which actually looks after the data) and a range of front-end products.

Oracle is the largest selling SQL based RDBMS and on the whole, is in my opinion, the most commercially useful. Major competitors to Oracle include: DB2 (IBM platforms only) Informix Ingress Sybase Others worth noting include Interbase from Borland (Unix/MS-DOS) shql (free UNIX tool works like ingress isql) various xbase products Postgres (Stonebraker's other work - free but unsupported except for the Net - which is about the same as commercial support anyway). It is *not* to be confused with the Oracle of Delphi, which led the market in executive information systems in the ancient world

Until about 7 BC. The chief data analyst (the Pythia) would get off her skull on steam and Laurel leaves and mutter gibberish (Said Quixotically on Laurel, SQL for short) which was then translated by priests in an ambiguous manner in order to please the end-user and thus extract a hefty donation. Probably the most famous bit of management information was to Croesus, (King of Lydia and known in the phrase "as rich as Croesus"), when he received the advice "If you attack the Persians, you will destroy a great empire". Well, he did attack, and lost his own empire. There's a moral to this story I think...

1.2. What are the advantages of Oracle? a. Portability Oracle is ported to more platforms than any of its competition, running on more than 100 hardware platforms and 20 networking Protocols. This makes writing an Oracle application fairly safe from changes of direction in hardware and operating system, and therefore a safe bet. One caveat, however, is that application using some constructs (such as field level triggers) may have to be reworked when porting them to a block mode environment. You can also develop a fairly fully featured application with little knowledge of the underlying OS. Personally, I have developed applications on OS systems barely knowing how to copy and edit text files. b. Market Presence Oracle is by far the largest RDBMS Vendor, and spends more on R&D than most of its competitors earn in total revenue. Oracle has the largest independent RDBMS market share in VMS, UNIX and

OS/2 Server fields. This market clout means that you are unlikely to be left in the lurch by Oracle and there are always

lots of third party interfaces supported and also, proficient staff are relatively easy to get. c. Version Changes Oracle seem very good at informing you in detail as to what is not going to be supported in the next major release and usually have some knob you can twiddle for good backward compatibility, or simply leave it working, but with "don't use this, use xxxx

instead" warnings in the manual. Backward compatibility is very good meaning you will not be in for an application re-write when You upgrade the DBMS. [Compare this with the Ingress v5-6 OSQL upgrade from hell.] I've worked with Oracle since V4 Beta and have never been in for nasty surprises as far as syntax goes. However, see "Version Changes" under disadvantages. d. Backup and Recovery Oracle provides industrial strength support for on-line backup and recovery and good software fault tolerance to disk failure. You can also do point-in-time recovery. Of course, you need the archive mechanisms and storage space to do this, but Oracle supports continuous archiving to tape devices spanning multiple volumes. e. Performance Speed of a *tuned* Oracle database and application is quite good, even with large databases. Oracle refer to 100 GB databases and I have personal experience administering 10 GB databases. The performance is not only "raw", but includes consideration of performance with locking and transaction control. f. Cursor Support

Oracle, like Ingress, but unlike Sybase (until Release 10 I think), supports cursors, which ease programming when performance is needed.A cursor basically lets you do row-by-row processing. Oracle supports multiple cursors per Oracle connection in line with ANSI standards.

g. SQL Dialect The dialect of SQL offered by Oracle is in my opinion superior to the others in the extensions it offers over ANSI-2, which is very much a lowest common denominator. Constructs such as the absolute function and decode keyword are very powerful Oracle additions to the standard SQL. h. Multiple Database Support Oracle has a superior ability to manage multiple databases within the same transaction using a two-phase commit protocol. This is best implemented in V7. You can fairly easily move where data is actually stored from node to node in a network and have data mirroring, making it easy to optimize the location of the data from time to time. This is not so easily done with offerings from other vendors or earlier versions of Oracle, where you were not able to update more than one database in the one transaction with any reliability. This meant that you could not move data around without recoding your programs. With V7, your DBA can optimize the location without pre-planning by Programmers or re-examination of the code prior to the move. i. PL/SQL PL/SQL, the procedural extensions, is a draft ANSI standard for procedural DBMS languages. See main discussion on PL/SQL. j. Declarative Integrity Oracle V7 supports declarative database integrity (the current ANSI standard) and V6 permit you to enter the declarations. With V6, you can get the toolset (such as SQL*Forms 3) to read

the declarations and automatically generate the required code. With V7, not even this is required, as the database engine automatically enforces the integrity. This means that you can open up your database to end-users through simple third party interfaces as they simply cannot break your business rules even even if they try. It makes it easy to administer changes in business and data rules as there is only one spot where the change needs to be made. This lowers the cost of required modification to the system because you do not have to edit all applications code that works with the table. It is reasonable to expect Oracle to release the first SQL-93

implementation at near-full compliance. As one DBA noted on the net recently "With Oracle V8 I'll be out of a job because everything will be in the file".

1.3. What are potential disadvantages of Oracle? Cost. Oracle isn’t cheap. At least before you consider costs of porting, programmer availability, etc, etc. Remember, you will almost certainly need a full-time DBA. Good DBA's are not cheap, but are worth their weight in gold. You will also need training for programmers and DBA's. Again, not cheap, but shop around - both for the cost of the courses and for the content. Oracle are not the only people who give Oracle training, and often a smaller consultancy can tailor a course for your needs and still be cheaper per training hour per person. If you are getting an application from a VAR, the Oracle components can often be obtained at a good price. Oracle is not (currently) as object-oriented as some of the competition. Implementation on some systems betrays the heritage of the system it was developed on (e.g. Mail REEKS of VMS) and can be Counter-intuitive to programmers used to their (non VMS or non UNIX) OS. On some systems, performance is not what you would (or were led to) expect, so you may need to upgrade your system. (The moral of this story is use systems that are inexpensively scalable). Joel notes particularly that IBM 9370 implementation is slow. (Hey, so is that news to us UNIX types?) While quite a few people have commented on buggy code, poor implementation, different keystrokes for different hardware, etc (All of which have some justification), this is in my opinion

generally a bit harsh. Sure, when comparing Oracle to more single-minded systems such as a compiler or programmer tool, Oracle comes of poorly in quality. But, remember you are talking about a large system and compare Oracle to other RDBMS systems and you'll find it actually isn't too bad. Just make sure the DBA runs each new release in a spare area for a while...

Version control of "source" for your applications in some products is painful where you do not have editable ASCII files. See the section on version control.

Version changes can give you nasty surprises. OK, so this affects everyone, but there have been a few "patches from hell". (Ask any VMS DBA who applied V6_36 or thereabouts). Personally I generally start feeling comfortable around Vx.0.15 but much prefer Vx.1). Historically, sales staffs were more prone to hyperbolae than your garden variety marketroid and technical support was poor. This has improved. Still, installation and upgrade scripts have copped a *lot* of flack in the newsgroup and I must admit to requiring a second pass at this sort of stuff, with a decent browse (and hack) through the install scripts in the meantime. Just as well I had disk and time to spare that weekend... Also, there has been quite a bit of criticism, at least here in Oz, of the way Oracle do not inform you about important patches to the RDBMS until you ring support with a problem...meanwhile your data just got corrupted. Apply pressure to your support representative to improve the situation. 1.4. What is SQL? SQL (often pronounced SEQUEL) formally stands for Structured (or Standard) Query Language. In common usage, however, it also encompasses the DML (Data Manipulation Language - for inserts, updates and deletes) and DDL (Data Definition Language - for structuring tables). The basic idea of SQL is to accept and process requests for the information you want without you knowing how to extract it (like you do for network databases). SQL is NOT the only language available for querying relational databases - the first versions of Ingress used "Quel", which had some advantages over SQL. Still, SQL came from IBM, implemented nicely by Oracle and became the de facto standard. SQL is the subject of international standards. SQL-87 is currently the lowest common denominator for most DB engines, but like any language, each vendor provides extensions to (and occasionally changes and omissions from) the standard ... SQL-93, still draft, handles procedural extensions. 1.5. What is PL/SQL? PL/SQL is a group of procedural extensions to the SQL language and is available to SQL*Forms (3.0 and above), SQL*ReportWriter (2.0 and above) and SQL*Plus (3.0 and above). Procedures written in this language are available to be stored in the database from version 7 of the core product. Currently, an ANSI committee is specifying procedural extensions

to SQL, and including these in SQL-93. Oracle PL/SQL was accepted as the first draft. SQL-93 is still at working draft stage, but the quick read I have had of it looks like fairly standard PL/SQL with a few extra statements thrown in. BTW, the spec is currently over 1K pages and *not* bedtime reading unless you like browsing a cross between legalese

and BNF! Come to think of it, excellent bedtime reading if you are an insomniac!

Early version of PL/SQL could have no direct I/O with the process sending it to the server. Forthcoming versions do. 1.6. What is Procedural Option? The procedural option to Oracle V7 permits you to define database triggers (e.g. a procedure to carry out when a record is updated, for example) and use DBMS PIPES, where an external procedure can effectively be called from one of these triggers. These triggers are written in PL/SQL. An example is as follows: create or replace trigger MY_TRIGGER after update on MY_TABLE For each row begin If updating ('MY_SCALAR') then Insert into MY_AUDIT_TBL ( AUDIT_KEY, VAL_NOW, VAL_PREV, DIFF, DT, WHO) Values ( MY_KEY, : new. MY_SCALAR, : old. MY_SCALAR, : new. MY_SCALAR -: old. MY_SCALAR, Sysdate, User); End if; End; Note the new keywords "new" and "old". This is similar to V6 and "Transaction Processing Option". Basically it contained most of the "goodies" of the new version and was licensed $erately. The TPO included sequences and the ability to run PL/SQL at the back end. 1.7. What products are available from Oracle? Apart from the core engine and consulting/education services... This list is NOT exhaustive. If I have missed anything, let me know, preferably with a quick review. 1. SQL*Plus Known in days of yore as UFI (User Friendly Interface), this is the basic "shell" for queries, basic reports and database

manipulation. It can be used interactively or driven from scripts. It is a must-have, as installation requires scripts to be run through this interface and most general administration by programmers will be carried out through it. Apart from the basic ability to issue SQL and PL/SQL commands, it has a number of extensions to permit programming (parameter

passing, variables, prompting for user input, etc) and report formatting. It operates identically across all platforms. 2. SQL*DBA A user-unfriendly version of SQL*Plus with extra power for DBA's. The history editing facilities of SQL*Plus have been removed so that you do not spend all your time in a product that has extra (needed but dangerous) capabilities to do things like start up and shut down your database. It also has general performance monitoring facilities. Oracle 6 SQL*DBA is mainly line oriented but has a screen oriented performance monitor. Oracle 7 SQL*DBA is entirely screen based by default (although you can invoke it as follows to get line mode) sqldba lmode=y 3. SQL*Net Needs to run on PC's and Mac's before you can access Oracle on other machines. Most mid-range and larger machines have it as part of the core product. Needs to be used on ALL machines to communicate across platforms or via a network. It is a separately licensed product for Unix,

MS-DOS and Macintosh versions and you need both compliant versionsto communicate between a client (which can be an RDBMS) and a server

(which must be an RDBMS). Note that if you are running mess-Windows, you can get into real difficulty as the SQL*Net driver cannot handle two cursors returning data the same instant - mainly because windows is not true multi-tasking. (Broken As Designed?). Mind you, SQL*Net v2 is out soon and even gets over the problem of OPS$logins when you do not actually log in to the Oracle server. 4. SQL*Async Gives functionality of SQL*Net but over a dialup-type line. 5. SQL*Connect SQL Based DBMS Gateways 6. Open Gateway SQL based and Procedural based DBMS Gateways 7. Net Interchange Software Protocol Converter 8. SQL*Forms A development tool for screen based applications that allows code to be stored in database tables. Version 3.0 and above use PL/SQL for procedural parts of the code.

Version 4 is coming out and has SQL*Menu facilities built-in. 9. SQL*ReportWriter Helps write reports and like Forms, permits source code to be stored in the database. Version 2, soon to be released, includes triggered events, the ability to update the database and uses PL/SQL. Version 1, on the other hand, is perhaps the one Oracle product tried and discarded by most sites. Despite improvements, Version 2 looks to be getting the same reputation. 11. Oracle*CASE A nifty set of data dictionary (once known as SDD) and design tools that let you model your database and processes and then generate reasonable first cut forms, etc from the definitions. The design sides need a GUI for model display. This product is good, like anything out of the Oracle UK group that used to be an independent company that Oracle purchased. Various reviewers have commented that while there are "me too" modeling and design tools, (and of course, no others take advantage of Oracle-specific enhancements), Oracle*CASE has the best capability to reverse engineer existing Oracle applications back into the modeling dictionary. Rumor has it that Oracle UK are currently working on extending this product to include CASE for languages like C et al. 11. SQL*Menu A suite of tools that allows the developer to enter menu details into a database and generate a menu from it. It integrates well with the other Oracle tools and has the capacity to produce quite useful end-user documentation. One nice feature is that a number of different menu appearances (full screen, pull down, lotus ring-like) can be generated from the same input specifications. Obsolete with SQL*Forms 4.

Nearly every DBA who has had to install SQL*Menu (on UNIX platforms at least) that I have spoken to had a hard time. Once that is done, however, it is easy to look after.

12. Oracle*Card Helps develop HyperCard like applications in Windows and Mac environments. 13. Oracle Glue Helps develop applications under MS-Windows that use things like Excel and Visual Basic, i.e. an API for DDE applications. It thus competes against the forthcoming Microsoft OBDC API. Sun and Mac versions of Glue are forthcoming. 14. SQL*Graph Prepares graphs from Oracle data. 15. SQL*Loader

Loads data from flat files into Oracle. Data can be loaded into more than one table at a time (e.g. if your incoming data is in the format of a master record followed by a number of detail records). 16. RPT/RPF An ancient reporting tool with a syntax like runoff that because of its ability to perform updates, is still used by some batch processes where its procedural capabilities are useful, especially where PL/SQL is not necessarily available and the developer does not want to put SQL in a compiled language like C. You need this for some aspects of Oracle*CASE. The RPT part is the program which goes through the tables and feeds data to the RPF (formatting part). If you are using this for reports you need more than a fair share of disk for temporary files, especially if the RPT part must finish before RPF can start the

formatting and there is a lot of data to process. It has advantages over SQL*ReportWriter in that the code is ASCII and HUMAN

READABLE, and can thus be put under version control tools. Also, it is a lot faster than SQL*ReportWriter and can be altered much quicker than wading through a m[ae]ss of menus.

Actually, my earliest comments about RPT/RPF were perceived as somewhat dismissive, and generated quite a lot of "fan-mail" for this product. 17. Pro*C, Pro*COBOL, Pro*Fortran... Precompilers that let you embed SQL statements into a standard language without *too* much trouble. While there are other means of accessing Oracle from languages such as C (the OCI for example), these interfaces are fairly low level and should probably only be used when you are being fairly sophisticated. While I cannot comment about languages other than C, the C code that comes out of the Pro*C precompiler is NOT really editable. Anyway, some of the function calls generated are specific to libraries that are part of the Pro*C product. Thus taking the generated C code to a site without a Pro*C license is probably not a good thing to do. 18. Data*Query A fairly new product that permits you to generate reports fairly easily. The nice thing about this (again from Oracle UK) is that if you have put constraints into the dictionary, then this will pick up those relationships, so you do not have to constantly specify the linking field between the EMP and DEPT tables, for example. It will also do break processing and allow you to define calculated fields easily so you do not have to retype them all the time. A suite of tables are kept internally, permitting users to have easy access to their own queries and with the ability to share queries among users. One nice feature for administrators is the ability to set a timed break on user queries to prevent "run-away" queries being generated.

There are still some limitations upon the number of tables that can be joined together, but DBA management of some appropriate views would solve this problem. 19. Data*Browser

Running under a window this gives graphical and analysis capabilities according to one reviewer and is pretty good.

20. Book Viewer Hypermedia application creating and viewing 21. co-author A grammar checking Utility 22. Oracle*Mail and Calendar/Scheduler

E-mail using Oracle to glue systems together across architectures. Betrays a VAX VMS heritage. Probably not a bad idea, using Oracle to glue together a mess of different architectures for mail, but why would you want to do that when there are other common standards for mail messages that will still work without needing Oracle up and running? For many common networks, such as those made of DOS, OS/2, Mac, UNIX and VMS boxes, if all you want is a common mail facility, there are probably better alternatives. A similar application provides office calendar information and is packages with Oracle*Mail as Oracle Office. 23. Oracle*Financials A BIG product with modules for accounting, human resources, etc. If you are a large company, worth considering if you have lots of disk and cash to spare. Even Oracle admit that if you are not a large company, it is not worth putting on your short list. It is reported to cost about $20K per user. 24. Oracle*TextRetrieval Lets you access text documents using queries. Next release (2) will support storage of common PC and Mac formats (e.g.MesS-Word and WordPerfect). Can do keyword searches. 25. Export and Import These produce files that can be migrated across architectures and can produce archives of a selection of tables, users and or indices. 26. Oracle*Terminal Terminal specification utility, that replaced the CRT suite used

by Forms 2.3. Lets you map logical key names, key help and display attributes to custom escape sequences. Offers much more power than CRT, but most of us DBA's could drive CRT. If ReportWriter

is the least used because of its limitations, Terminal is the second least used, because the documentation is limited and it is hard to see how it all hangs together. Please someone, send in some hints.

27. Oracle*Alert Lets you define certain conditions that when met trigger an event, usually an Oracle*Mail message, to someone. For example, if monthly sales go to low, fire off a message to the sales

manager. 28. SQL Modules

Currently in beta is the V1.0 support for Oracle in host languages not including Embedded SQL but according to ANSI Standards.

V1.0 requires Oracle V7.1 and is scheduled for production with 7.1 production version. Languages supported will be Ada, C, COBOL and FORTRAN and follows the 1989 ANSI standards with some of the low-level 1992 standard. Also lets you call stored procedures. Limitations are one SQL statement per procedure, no DDL, no

dynamic SQL, no multiple concurrent connections. Full (ish) SQL92 expected with V2.0.

.... It should probably be noted that Oracle*Forms (4.0), Oracle*ReportWriter (2.0), Oracle*Graphics (2.0), and Oracle*Menu will be all integrated together into one large Oracle*Tools package, the CDE (I think it stands for Common Development Environment). Oracle V7 needs a "procedural option" for database triggers, etc. Oracle 7.1 has been announced and will include Parallel Query and Multi-Media extensions. Alpha Now, Beta mid year, Production end of year.

Oracle 8 is slowly being revealed and will include Object Oriented extensions, and specialized servers for images, video, sound,

text, and SQL RDBMS. Looking at the SQL-93 spec will give you a glimpse at the way this will move -- abstract data types are defined, etc.

1.8. What Public Domain interfaces are there? Not Public Domain but free include various tools that Oracle will distribute *when* you ask for them. These are utility scripts written by the Oracle Performance Group UK. I was given them and told that they were copyright by Oracle but freely distributable. They do things like take snapshots of internal SYS.V$* tables (one set for V6, one for V7), analyze forms 2, libraries of mathematical functions for forms 3. It includes a version 6 database defragmenter in Pro*C; (V7 automatically defrags). It is usually distributed as a UNIX tar file on a DOS floppy names dostools.tar. Third Party Freebie Tools available include... 1. Oraperl The Oraperl patches to perl are available from comp.sources.misc archives and were written by Kevin Stock. These patch perl from Larry Wall (see GNU or comp.sources.unix archives and Comp.lang.perl newsgroup) to give it access to Oracle at a fairly basic level, permitting you to even have simultaneous connections to one or more databases (e.g. under different

Oracle logins). The perl language is available (as far as I know) for UNIX, VMS, DOS, OS/2 and Macintoshes and is a cross between the UNIX shell and C, and gaining rapidly in popularity. One major advantage is that it makes many C libraries available for use in an interpretive script language, and is thus more powerful than the shell. One of the useful things that comes with Oraperl is a script that takes an SQL statement from a command line and executes it. Another useful script takes a table and turns it into a series of INSERT statements. The current version of Oraperl is 2.004 (version 2, patchlevel 4). You can get it by FTP or a mailserver from any comp.sources.misc archive site, for example: USA: wuarchive.wustl.edu [128.252.135.4] Australia: archie.au [139.130.4.6] The directory should be something like: usenet/comp.sources.misc/volume3[0-9]/oraperl-v2/* There are five parts and four patches.

Note that you need to get perl (and check it compiles as is), from any GNU archive site (e.g. archie.au in ~ftp/gnu). I am using

perl v4 patch 36 at the moment with oraperl v2 patch 3. I will put in patch 4 soon. Version 5 of perl is currently in alpha release on ftp@netlabs.com. The availability of other patches to perl such as curses lets you use screen-handling functions. There is also a GUI development environment that sits on top of Tcl/perl that could use oraperl instead and thus create an X-windows/Oracle development platform. This is called WAFE. [Also available are perl patches to Sybase, Ingress and RDB. You could possibly link them all together, although the SQL functions have different names and syntax depending on which interface you are using.] I have posted a separate FAQ for oraperl that I obtained from Kevin. 2. DBperl Soon to be available is DBperl, which unifies the syntax of the Sybase and Oracle patches to perl. It will also permit access to Ingress and Interbase, with consideration now being given to xBase requirements. There is a mailing list, <perldb-interest@vix.com. You can mail <Perldb-interest-request@vix.com to receive it. This contains stuff similar to the files that flow through this newsgroup, so a fair bit of it is technical discussion on the innards of DBperl which may not be to your interest. As soon as I find

about releases, I will announce it in this FAQ. Nevertheless, now is your chance to put in your wish list and comment on the design of the API. You can get perl-related stuff (including individual perl interfaces to Sybase, ingress, Informix, etc) from Ftp.demon.co.uk 3. Unload Another utility is unload (which a lot of people rename to sqlunload). It takes a SQL statement and creates two files, a data loader control file and the data file. I think this was in comp.sources.misc. I'll post it up to comp.databases.oracle if need be (I forget where it came from originally). If anyone Knows where it comes from and where it is archived, let me know. I have tried to contact the author, but mail bounces. 4. TCL extensions TCL is a GUI oriented language. Tom Poindexter has extended it (Pretty much like perl is extended) to permit access to Sybase and Oracle. Tom can be reached by tpoindex@nyx.cs.du.edu and the extensions should be available from the TCl archives at harbor.ecn.purdue.edu. Further information would be available via the comp.lang.tcl newsgroup. TCl/Tk is also available from Sprite.berkely.edu 5. XSQL Just written by Jeff Stander, this takes an SQL statement and sends the results to an X-window. See credits for his address. 6. Other GUI interface application builders Now, I do not know too much about the following, but they could be useful for you: XView from xview.ecdavis.edu Xtpanel (used by XSQL) from lth.se 7. Documentation While they are still in draft mode, SQL93 standards are available via gatekeeper.dec.com:~ftp/pub/standards/sql A description of ODBC is available on Windows archives cica and Mirrored monu6.cc.monash.edu.au: ~ftp/pub/win3/programr/odbc.lzh. These are WinWord documents and are written using strange styles, fonts and with missing graphics. If your desperate for doco, have a look and see if you feel like spending the time to make them readable. 1.9. What third party interfaces are available? Heaps. Oracle interfaces are usually the first RDBMS interface a third party tool vendor will support. If you are on a PC, look at Q+E that comes with Excel 4 for Windows, providing you have SQL*Net. (Mind you, this is an old, cut down copy of Q+E). Some interfaces written mainly for the UNIX world support a number of databases. Two examples I have used and found OK were

JAM (from JYACC) - good for C programmers who wanted to write forms quickly, and UNIFY - which also supports its own backend if you do not have Oracle (or Ingress or ...) Other front-end tools include Gupta SQLWindows, (which can also be used for its own database). MS-Access and ODBC is fairly new. One criticism is that you are prevented from using the native SQL (which removes the ability to use Oracle extensions) because the front-end product is too "smart" and builds the SQL for you. However, if you ask Microsoft *nicely* they will give you access to a routine that you can send a straight SQL statement to that is passed to the backed RDBMS without modification, thus bypassing this problem. (Don't you hate mushroom treatment?) Some more detailed product notes follow. Q+E Range of Products --------------------- Platforms: MS-Windows, OS/2 Requires: SQL*Net if connecting to Oracle Product Range: Broad range of products: ODBC development kit If you want to write your own ODBC driver ODBC 12-pack ODBC drivers for common databases Database library "Large" model for Microsoft C. Many databases supported. include xbase and ASCII files SQL used is native to the host DBMS. xBase includes many functions ASCII files are R/O either delimited or fixed Most functions also supported in MS VisBasic. (Those fiddling with pointers are not) Royalties on run-time. DLLs required. Database Editor Version 2 comes bundled with Excel4 for Win. Version 5 can be bought as an upgrade, and is well worth looking at. Permits easy generation of queries from various sources and generation of summary information. End users can build a parameterized query and then save it. Has forms and report painter. Can edit SQL text directly. Has script ability for talking via OLE and DDE and permitting multiple commands. (No IF, WHILE type constructs tho). Comes with connect library for driving Q+E from C, Visual basic, etc. Comes with demo templates for WinWord, add-ins for Excel, Ami-Pro, Actor, C and

VisBasic. Less common ODBC drivers are also available. Contact: Pioneer Software (US) developed it. In Australia, contact Azonic in Sydney. (02) 878-6600 Other Notes: Most comments about these products are very favorable and generally include the terms "rugged" and "well-designed". Rumor has it there are quite a few ex-Oracle guys at Pioneer. IDAPI will be supported, but ODBC is preferred. Apparently someone in Finland markets an OO C++ extension to the database library. Do not know if you can open two different types of DB at once - that would be really useful. Clear Access ------------ Platforms: Macintosh and MS-Windows Requires: SQL*Net Features: 1. Point and click SQL data retrieval to applications such as MS-Excel or flat files. 2. Script manager 3. Can link applications directly to SQL servers, e.g. An Excel macro button can populate a worksheet. 4. Supports DAL. Pricing: $450 (US?) lists per station, but there are volume discounts. Contact: Clear Access Corp, 200 West Lowe Fairfield, and Iowa 52556 (515) 472-7077 FAX (515) 472-7198 Other Notes: Got this info from the vendor. Have heard no reviews. JAM from JYACC -------------- Platforms: MS-Windows, Motif, Open Look, and Character Based DOS, UNIX Requires: SQL*Net Features: 1. Can use various other formats 2. More flexible validation than forms triggers 3. Can be real-time 4. Easy C interface Pricing: ? Contact: US: 800-458-3313 International: 212.267.7722 Fax: 212-608-6753 Other Notes: Once worked in an R&D shop we others in the team were using this. They were very happy with it. Will appeal to C and UNIX programmers particularly because it integrates so well with C. It seemed to be designed with uncompromising Code-cutters in mind. Not for cowboys and novices. One of the cute things was the ability to use UNIX regular

expression matching on fields as part of standard validation. SQR --- Platforms: Various OS and databases Features: 1. Report generation language 2. Can update the database 3. Normal OS file interface capability Contact: US: Australia: Sequel P/L, Melbourne Other Notes: Good if you have different database and OS platforms and want to use similar code. I used it for a short time a few years ago, but others I trust who used it more loved it. Quite popular. PowerBuilder ------------ Developer tool for management of databases and generation of front-end forms and reports. Platform: MS-Windows Features: Some CASE and OO constructs for front-end A few internal CASE tables for back-ends Can generate ASCII files of DDL (No triggers or procedures) Looks useful as a working DBA tool as well. Interfaces to most common RDBMSs. Contact: Powersoft, the developer. Other Notes: Smells of original design for Sybase. SuperNOVA --------- Platforms: MS-Windows, Motif, OpenLook UNIX, MS-DOS, VMS Oracle, Sybase, Ingress, Informix, C-ISAM, Teradata Contact: Four Seasons Software, Bilthoven, Holland. Fax: +44 81 446 9143? Phone: +44 81 446 6481? SQL*ETON -------- Meant to be like "skeleton" for Oracle Forms development. Features: Application development skeletons and utilities Uses standard Oracle tools E.g. Straight forms; no user-exits Can retrofit existing forms. Contact:

Logical Technologies Pvt. Ltd. 2nd Floor, 535 Flinders Lane, Melbourne, Vic, 3000, Australia Ph: +61 3 629 5200, Fax: 629 8383 Notes: Logical also makes Forms 2.3 to 3.0 converters - more on this soon. They also have "Definition", an alternative to SQL*Case. If anybody reading this is a user or vendor of a particular third party interface that you think should be mentioned, mail me

direct rather than via the newsgroup together with a quick summary.This section needs expanding and correction.

1.10. How portable is Oracle applications to other RDBMS? While the core SQL is portable, each vendor has their own extensions and ways in which you need to structure the data model to take advantage of the way each RDBMS does things. To get any real performance, you need to take advantage of the extensions, or be stuck with a lowest common denominator. Examples of extensions include functions available to SQL (such as decode), query constructs (such as the hierarchical CONNECT BY PRIOR and outer join constructs) and physical storage parameters. Not only this, but the languages used to implement non-SQL operations and the various tools are not compatible across different RDBMS systems (again, unless you use a third party tool such as Unify). 1.11. What Query Optimizers are there? Oracle <= 6 has rule based optimization that depends on two things, the presence of indices and the way you construct your where clause. Oracle 7 has the option of using a statistical optimizer. This requires you to run jobs that get a statistical picture of the spread of data values in columns across your database. This information is used to help decide how to perform the query. The data collection can be very intensive and take ages (unless you use the ESTIMATE option which helps a lot) and run regularly as the population of your database changes lest your queries suffer from being optimized using misleading data. Note that the ESTIMATE function only scans the first part of the table, which may not be representative of the whole table. In The Future: I’ll be bringing in edited highlights of Tina C. London's discussion on how to optimize queries using the V6 rule-based optimizer and how to use EXPLAIN PLAN. 1.12. Is there an anonymous FTP site for Oracle stuff? In Germany, one has been started up by Andreas Bartlett. Ftp.Uni-Oldenburg.DE: /pub/Unix/oracle It is mostly empty now, but he says to feel free to upload. In the USA, Andy Finkenstadt, is starting one up soonish Ftp.vistachrome.com

A more general site, best known for storing DBperl stuff is ftp.demon.co.uk: /pub/perl/DBperl/oraperl Which is growing a suite of oraperl programs. 1.13. What mail lists are there? Apart from those that Oracle run if you have Oracle Support.... I heard rumors about an "orawiz" mailing list that had possibly shut down, but here are notes on what I do know. Name: ORACLE-L (ORACLE database mailing list.) Mail Address: ORACLE-L@SBCCVM.BITNET List Server Address: LISTSERV@SBCCVM.BITNET LISTSERV@CCVM.SUNYSB.EDU To Subscribe: Send "Subscribe ORACLE-L Fred J. Nerk" command to list Server address To Unsubscribe: Send "SIGNOFF ORACLE-L" commands to list server address *NOT* to mail address Archives: Send "INDEX ORACLE-L" to list server address for info Extra Notes Send "INFO REFCARD" to list server address to get reference Send "INFO DATABASE" to list server address to get search notes Has just started activity again after a quiet period. 1.14. What bulletin boards are there? I do not have the details, but I heard of a BBS called SQLware or

Something that only charges an annual fee. Does not specialize in Oracle. Have no further details. Would love them and a list of the sort of stuff they carry (hint). Unfortunately, it is not a local call to the States from here!

Oracle themselves set up a bulletin board for customers with Support. Some local user groups are setting up there own bulletin boards. One is the Victorian Oracle Users Group here in Australia. Are there any others? 1.15. What news groups are there? You probably already know of comp.databases.oracle (where you Picked this up). Comp.databases is not bad for general questions not related specifically to Oracle problems or techniques. There are other comp.database sub-groups such as theory, ingress, Sybase, Informix and xbase. BTW: On all these information access media, *PLEASE* keep traffic down by editing severely when you are quoting another mail. Also, if you post an question, it is useful and polite to post a summary of replies and solutions back. For these, prefix the subject with "SUMMARY:". This enables quick selection of

Important information from the group or your mail and allows sites to keep only summaries. I am not trying to dictate, only speak from the point of view of someone snowed under who wants to be able to vgrep mail and news easily.

1.16. How does Oracle compare to...? OK, I'll admit this section is purely personal. My asbestos Suit is on. Mail comments if you feel strongly. Sybase: I would be most likely to choose Sybase if Mainly OS/2 site Ingress: Oracle has better SQL Oracle has more robust backend Oracle is more portable Oracle has more flexible security. Ingress front-end tools are niftier I would be most likely to choose Ingress if Most using X-terminals on UNIX host Had DBA with good UNIX SysAdmin skills Informix: SQL interfaces can "pipe" output of SQL SELECTS through a host UNIX command. Nifty! Has SQL dialect like cross of Ingress and Oracle. I would be most likely to choose Informix if Hosted under UNIX on small systems Dollars were scarce DB2: I would be most likely to choose DB2 if What? Me? In an IBM shoppe? 2. SQL QUESTIONS ----------------- 2.1. How can I avoid a divide by zero error? Use the DECODE function. This function is absolutely brilliant and functions like a CASE statement, and can be used to return different columns based on the values of others. For example, assume we sell products at variable cost, depending on the ability of the purchaser to pay (e.g. academic discount). Our table includes the following columns, PRODUCT, (the key) NUM_SOLD, TOTAL_REVENUE. Average sell price should be TOTAL_REVENUE / NUM_SOLD, but if we have not sold any, we are in trouble. We can avoid this by returning NULL as the result if NUM_SOLD is zero as follows: select PRODUCT, Decode (NUM_SOLD, 0, NULL, TOTAL_REVENUE/NUM_SOLD) AVG_SELL_PRICE

from my_table; OK, so that is one problem solved, but DECODES is much more Useful and it is worth giving a couple of more examples: Select decode (SEX_CODE, 'M', 'man', 'm', 'boy', 'F', 'woman', 'f', 'girl', 'Unknown’) ... In the above example, SEX_CODE would be a single character code, and the statement would return a description based on that code or "unknown" if there was no match. Decode is especially useful if you even want to choose different information from two tables: Select decode (EXPR_1, EXPR_2, TBL_1.COL_1, EXPR_3, TBL_2.COL_1, TBL_1.COL_2) from ... The DECODE function is always worth keeping in mind. Many times, it will be your only way to do what you want in a tricky bit of SQL. 2.2. Can I update tables from other tables? Yes. For example, if we had a table DEPT_SUMMARY, we could update the number of employees field as follows Update dept_summary s Set num_emps = (select count (*) from emp e Where e.deptno = s.deptno); 2.3. Can I remove duplicate rows? Yes, using the ROWID field, which *will* be unique. There are many variations on this statement, but the logic will work. This assumes an EMP table keyed on EMP_ID, which is NOT NULL. Delete from EMP e Where not e. ROWID = ( Select min (f. ROWID) from EMP f Where f. EMP_ID = e. EMP_ID); I'll get the OFFICIAL statement according to Oracle sometime.

The other good thing about ROWID is that it is the quickest way to reference a particular row in a table, providing that no table

reorganization happens in the meantime. A possible use is to select information from a table including the row number into a block in SQL*Forms, and pass the ROWID to a user-exit that goes and picks up the LONG RAW in that table and displays it as a

picture. 2.4. Can I update using a view? Only if the view is a simple horizontal slice through a single table. Columns from the base table can be omitted from the view if they are NOT NULL. Note that views can be created with a check option that prevents you using the view to insert records Contravening selection criteria for that view. 2.5. Are views automatically updated when I update base tables? Yes, that is the whole idea of views. The only thing Oracle stores for a view is the text of the definition. When you select from a view, Oracle looks up the text used to define the view and then executes that query. 2.6. Should we use complex views that cruel performance? Because view queries that involve sorting, grouping, etc can lead to a high performance overhead, it might be better to write some reports with a procedural component that fills up a temporary table and then does a number of queries from it. While this is non-relational, it can be justified for some cases. Nevertheless, it is useful to have the view definition in the database. You can then test the output from the view against the output from your procedural manipulations. The view definition can also be used as the unambiguous gospel. 2.7. Can I implement tree-structured queries? Yes! Those migrating from non-RDBMS commonly ask this Apps. This is definitely non-relational (enough to kill Codd and then make him roll in his grave) and is a feature I have not seen in the competition. The definitive example is in the example SCOTT/TIGER database, when looking at the EMP table (EMPNO and MGR columns). The MGR column contains the employee number of the "current" Employee’s boss. You have available an extra pseudo-column, LEVEL, that says how deep in the tree you are. Oracle can handle queries with a depth up to 255. Select LEVEL, EMPNO, ENAME, MGR from EMP connect by prior EMPNO = MGR start with MGR is NULL; You can get an "indented" report by using the level number to Substring or lpad a series of spaces and concatenate that to the string. Select lpad ('’, LEVEL * 2) || ENAME... You use the start with clause to specify the start of the Tree(s). More than one record can match the starting condition. One disadvantage of a CONNECT BY PRIOR is that you cannot

Perform a join to other tables. Still, I have not managed to see anything else like the CONNECT BY PRIOR in the other vendor Offerings and I like trees. Even trying to doing this Programmatically in embedded SQL/C is difficult as you have to do the top level query, for each of them open a cursor to look for child nodes, for each of these open a cursor .... Pretty soon you blow the cursor limit for your installation.

The way around this is to use PL/SQL, open the driving cursor with the CONNECT BY PRIOR statement, and "join" programmatically for each row returned.

2.8. How can I get information on the row based on group information? Imagine we have the EMP table and want details on the employee Who has the highest salary. You need to use a subquery. Select e.ename, e.empno, e.sal from emp e where e.sal in ( select max (e2.sal) from emp e2 ); You could get similar info on employees with the highest salary in their departments as follows Select e.ename, e.deptno, e.sal From EMP e where e.sal = ( Select max (e2.sal) From EMP e2 Where e2.deptno = e.deptno ); 2.9. How can I get a name for a temporary table that will not clash? Use a sequence, and use the number to help you build the Temporary table name. Note that SQL-93 is developing specific Constructs for using temporary tables. 2.10. How can I find out about what tables, columns and indices there are? Oracle maintains a live set of views that you can query to tell You what you have available. In V6, the first two to look at are DICT and DICT_COLUMNS which act as a directory of the other dictionary views. It is a good idea to be familiar with these. Not all of these views are accessible by all users. If you are a DBA you should also create private DBA synonyms by running $ORACLE_HOME/rdbms/admin/dba_syn.sql in your account. 2.11. Is there a formatter for SQL statements? There are a number of "beautifiers" for various programs languages. The cb and indent programs for the C language spring to mind (although they have slightly different conventions). As

far as I know there is no formatter for SQL available. Given that a public domain SQL parser is available, maybe someone could base

a reformatted based on the grammar definitions therein. Note that you CANNOT use cb and indent with Pro*C as both these Programs will screw up the embedded SQL code.

2.12. What is the DUAL table? The DUAL table is a table with a single row and a single column used where a table is syntactically required, for example in SQL*Forms 2.3 where you want to use a function available to SQL. E.g. If we have two fields, x and y and we want y to be set to a substring of x Select substr (x, 2, 4) into y from dual; If DUAL has NO rows or more than one, many forms under 2.3 syntax (or 2.3 triggers in forms 3) will not work properly. At worst, the logic of some of the triggers in your form will be reversed, without any message to the user and data could be destroyed. When I was writing Forms 2.3 code, the *first* thing I did was to check that there was one row (and only one row) in the DUAL table, otherwise I displayed a message to contact the DBA and then quit the form. This was done in KEY-STARTUP. 2.13. What is the difference between CHAR and VARCHAR? Oracle have stated that CHAR will become fixed length character type at storage level, and that VARCHAR will be variable length. Currently they are synonymous. This will probably mean that CHAR types will not be able to be NOT NULL, and will take up all the storage required when the record is first inserted. Currently, the only physical storage required is the actual data and a length specifier. It may also mean that restrictions such as where RESPONSE in ('YES', 'NO') may have to be rewritten for CHAR types as where RESPONSE in ('YES', 'NO ') At the level of Pro*C, of course, they are markedly different. BTW, the behavior of CHAR will be able to be altered by a PFILE

Setting affecting V6 compatibility. With V6 compatibility ON, the CHAR will be the same as V6. With compatibility OFF, CHAR will be

padded and VARCHAR will be a true varchar.

There are some performance gains that MIGHT be possible with paddedStrings: if the initial strings or keys are padded, then the back-end Engine can quickly skip to the field rather than scanning for field delimiters.

2.14. What is ROWNUM good for? ROWNUM is a pseudo-column returned as rows are selected and gives you a number for the row. "Fine", say a lot of people, "I will use it to peel off the first few rows by using (ROWNUM < n) in a WHERE clause". The problem with this is that ROWNUM is evaluated BEFORE the sorting (though after the WHERE). Try the following to see my point. select ROWNUM, DEPTNO from EMP where ROWNUM < 10

Order by DEPTNO, ROWNUM When you think about it for a minute or two, it cannot be any other way! However, ROWNUM is good when you want to get a UNIQUE reference for each row returned, as long as you do not mind the order! 2.15. How do I get a top ten?

This question gets bandied around from time to time and the answer is often given just to use ROWNUM (see above). However, what you have to do is order them first, then get the first ten. Some answers included creating a temporary table created by a select with an order by and then select from the temp table where ROWNUM<10. This will not always work.

I do not believe that straight SQL is the way to go for such problems when you have PL/SQL available.

My approach would be to use a PL/SQL cursor to select the ordered data and abort the loop after 10 records. If using Pro*C, you do

not even need a temporary table. If you are using a temporary table then you will not need it to be as big as the original, which straight SQL will do.

2.16. How can I control the rollback segment I use? In SQL, you may need to control the rollback segment used as the default rollback segment may be too small for the required transaction, or you may want to ensure that your transaction runs in a special rollback segment, unaffected by others. The statement is as follows: SET TRANSACTION USE ROLLBACK SEGMENT segment_name; On a related note, if all you are doing are SELECTS, it is worth telling the database of this using the following: SET TRANSACTION READ ONLY; Both these statements must be the first statement of the transaction. 2.17. How can I order a union? Use the column number. Say we are getting a list of names and codes and want it ordered by the name, using both EMP and DEPT tables: select DEPTNO, DNAME from DEPT union select EMPNO, ENAME from EMP order by 2; 2.18. How can I rename a column? There is no way a column can be renamed using normal SQL. It can be done carefully by the DBA playing around with internal SYS dictionary tables and bouncing the database, but this is not supported. (I have successfully done it in V4 thru V6. Have

not tried it with V7.) 2.19. Who are SCOTT/TIGER, SYSTEM and SYS? These three users are common in many databases. SCOTT is the standard demo user, with TIGER as the password. SYSTEM/MANAGER is a DBA account that runs the internals as far as supported use

goes and SYS/CHANGE_ON_INSTALL actually owns the internals. It is dangerous to fiddle with objects owned by SYS.

Another common user/password is PLSQL/SUPERSECRET used for PL/SQL demo stuff.

Oh, and don't complain about the passwords being told here. These are default passwords. For SYSTEM and SYS they ***MUST*** be altered for security reasons. After all, everybody knows them.

2.20. Who do various access methods compare? How you organize your SQL and indices controls what access methods will be used. The following ranking is valid for V6. I do not know about V7. QUERY PATH RANKING (lowest rank is the best) Rank Path 1 ROWID = constant 2 Unique indexes column = constant 3 Entire unique concatenated index = constant 4 Entire cluster key = corresponding key in another table in same cluster 5 Entire cluster key = constant 6 Entire non-unique concatenated index = constant 7 Non-unique single column index merge 8 Most leading concatenated index = constant 9 Index column BETWEEN low AND hi or LIKE 'C%' 10 Sort/merge (joins only) 11 MAX/MIN of single indexed column 12 ORDER BY entire index 13 Full table scans 14 Unindexed column = constant or column IS NULL or column LIKE '%C%' 2.21. What are clusters? Clustering data is a technique where the storage of records of related tables is intermixed, with the dependent records of one table in the same block as those of the master record. The logic behind this is that you probably most use the dependent records after you have accessed the master table. That’s all fine, but having a table in a cluster prevents you from dropping one and not the other. Also, the master and dependent records of other tables must fit into an Oracle block, typically 2k (though adjustable at install time by a brave DBA). Now, if you are thinking of cluster transactions with an account master record, how long before you have blown 2k ?

No Oracle DBA I ever knew, apart from Oracle staff, thought that using clusters was worth the hassle. 2.22.How can I update a big table without blowing rollback segments?

Imagine you have a HUGE table and need to update it, possibly updating the key. You cannot update it in one go because your rollback segments are too small. You cannot open a cursor and commit every n records, because the cursor will close. You cannot have a number of updates of a few records each because the keys may change - causing you to visit records more than once. The solution I have used was to have one process (with SET TRANSACTION READ ONLY) select ROWID from the appropriate rows and pump these (via standard I/O) to another process that looped around reading ROWIDs from standard input, updating the appropriate record and committing every 10 records or so. This was very easy to program and also was quite fast in execution. The number of locks and size of rollback segments required was minimal. 2.23. Why don't I get records for the date I want? You are trying to retrieve data based on something like: SELECT fld1, fld2 FROM table WHERE date_field = '18-jun-60' You *know* there are records for that day - but none of them are coming back to you. What has happened is that your records are not set to midnight? (Which is the default value if time of day not specified). You can either use to_char and to_date functions, which can be a bad move regarding SQL performance, or you can say WHERE date_field = '18-jun-60' AND date_field < '19-jun-60' An alternative could be something like WHERE date_field between '18-jun-1960' and to_date('23:59:59 18-jun-60', 'HH24:......YY') 3. SQL*PLUS QUESTIONS ----------------------3.1. How can I control the startup configuration of SQL*Plus?

SQL*Plus first looks at a login.sql (global login) in a Directory underneath the main Oracle installation directory ($ORACLE_HOME/dbs/glogin.sql for UNIX) and then in login.sql in your CURRENT directory. I think the VMS login file is in SYS$ORACLE, but I am not sure about that. Late item: someone reported glogin.sql in another directory: $ORACLE_HOME/sqlplus/admin, but I am not sure of which version and platform. I only REPRESENT the directory as a UNIX path, I do not know whether it was UNIX or not. Actually, I think $ORACLE_HOME/sqlplus/admin is a much better place for it.

It is a pity that Oracle does not use a file in your $HOME Directory, but I have hacked glogin.sql to use a file in the $HOME if it exists. Another alternative is to set an environment variable SQLPATH (I.e. $SQLPATH in UNIX, %SQLPATH% in MS-DOS, and probably a logical in VMS) that points to the directory where the login.sql file is to be read, rather than the current directory. This can include more than one directory, separated by colons (in UNIX, that is ... MS-DOS probably uses semi-colons as delimiters) with the first login.sql found being the one that is used. 3.2. Can I get a column value into a substitution variable?

Use the OLD_VALUE spec with the COLUMN command. Imagine we want the surname of an employee to go into a variable, getting it via the employee id. COLUMN x OLD_VALUE y SELECT surname x FROM employee WHERE emp_id = 1234; PROMPT I found employee with surname &&y Of course, this was more often used as a kludge before PL/SQL became available in SQL*Plus (or if you had v6 without TPO), but it is still useful for a number of things. Note that some people prefer to use the NEW_VALUE directive rather than the OLD_VALUE directive. For this example where only one row is returned, it does not make much difference. 3.3. How can I change the (hated default) editor to my favorite?

When you type "edit" to SQL*Plus, it invokes a default editor for your system. On DOS this is often EDLIN, on UNIX ed and on VMS, it is usually EDT. In your login.sql file (or preferably the glogin.sql file set up by your DBA), you should set the variable that changes this to your favorite editor. A possibility for UNIX: define _editor=" /usr/ucb/vi" A possibility for VMS: define _editor="EVE" 3.4. What is the difference between & and &&?

You can create a "permanent" definition of a substitution variable using DEFINE, the OLD_VALUE or NEW_VALUE clauses of a COLUMN statement (when the SQL statement uses them) or by referencing the variable with &&. Use of a & does not create a permanent version and will prompt you for a value if the variable does not exist (as will &&). However, next time you reference the variable with & or &&, it

will ask you for the value again. Try the following to figure it out (do not enter the "SQL" and remember to type something in when asked, make it different each time). SQL undefine try_1 SQL prompt &try_1 SQL prompt &try_1 SQL prompt &&try_1 SQL prompt &&try_1 SQL prompt &try_1 SQL prompt &&try_1 Note that use of positional parameters (&1, &2, &3....) are slightly different, they are given a "permanent" definition. P.S. When I say "permanent" I mean permanent for the current process. 3.5. What is the difference between "host" and "!”?

The host and! (Sometimes another character) both create operating system commands as child processes of SQL*Plus. The difference is that the "host" will perform variable substitution of & or && symbols, whereas "!" will not. Note also that the default shorthand character varies with platform. Under VMS, you use the $ symbol. 3.6. Why can't I use a table name in a substitution variable?

Often, people try and put a table name in a substitution variable and then use it as follows: define WORK_TABLE="EMP" select &&WORK_TABLE.DEPTNO from &&WORK_TABLE; Mind you, the substitution in the "from" clause is OK. What is happening is that the "." between &&WORK_TABLE and DEPTNO is a terminator for substitution. Thus define XYZ="ABC" prompt &&XYZ.abc will give "ABCabc" Thus, you should have used Select &&WORK_TABLE.DEPTNO from &&WORK_TABLE; (You can change this meaning of "." if it bugs you use the SET command with the CONCAT argument but I do not recommend changing it without lots of thought).

3.7. How can I see all of a LONG?

First of all, the following might be useful SET MAXDATA 32767 SET ARRAYSIZE 1 You should then SET LONG 5000 SET WRAP and maybe use COLUMN xxxx FORMAT A60 WORD_WRAP for it. Oh yeah, if there is a hex display function in Oracle SQL, but you can't use it on a LONG when you need it. You should also know something of the SET parameters and ensure you do not go outside system limits. MAXDATA Maximum total buffer size ARRAYSIZE Number of records buffered LONG Characters of a long "seen" RecordSize * Arraysize must be less than MAXDATA. Note that ARRAYSIZE defaults to 10 or 20, and you will probably blow the MAXDATA extracting large LONGS so check these out and put appropriate SET statements in your script. It is worth having a couple of library scripts in Oracle that look after these parameters in a co-ordinates way so that other scripts could simply start $ORACLE_HOME/local/plus/set4long TRUE or start $ORACLE_HOME/local/plus/set4long FALSE 3.8. How can I force a column to begin on the left of the page? Use the COLUMN FORMAT command with FOLD (BEFORE|AFTER). 3.9. Can I alias SQL commands? There is no real alias mechanism in SQL*Plus, but you can do something similar using && variables. 3.10. Can I escape significant punctuation marks?

Many UNIX-oriented users like to have a general "escape" character to remove the significance of special characters. They want to be able to refer to a real "&" using \&, for example.

Well, you cannot. [Hint to any of you at Oracle]. What you have to do is check out the SET command parameter that is specific to the character you were interested in and change it. For example: rem alter the character set define "~" select "This & that are normal" from dual; accept your input prompt "Give me a string" Select ~your input from dual; Set define "&" Now this is fairly painful if you want keep track of things and

there are some characters you cannot escape. Do a "SHOW ALL" and you'll see all the various things you can play with. 4. SQL*FORMS 3 QUESTIONS -------------------------4.1. How can I get a list of values from a hard coded list?

Assume the field is SEX_CODE, use the following in the List-of-values SQL statement SELECT 'M', 'Adult Male' INTO SEX_CODE FROM DUAL UNION SELECT 'F', 'Adult Female' FROM DUAL UNION SELECT 'm', 'Juvenile Male' FROM DUAL UNION SELECT 'f', 'Juvenile Female' FROM DUAL UNION SELECT 'U', 'Adult Unknown' FROM DUAL UNION SELECT 'u', 'Juvenile Unknown' FROM DUAL It's for a zoo catalog of animals... :-) 4.2. How can I get find to look at description with list of values? Imagine that you are have the following list of values text for a key (e.g. for the DEPTNO field of the EMP block): Select DEPTNO, DNAME, LOC into: EMP.DEPTNO from DEPT The list-of-values find capability only works on the first field however, which is next to useless. To get the searching on the name, you need to put the name first in the SELECT clause. Of course, it needs somewhere to go, so you need to have a field (GLOBAL variables won't work) that you use as a bitbucket. Select DNAME, DEPTNO, LOC into :CONTROL.BITBUCKET, :EMP.DEPTNO from DEPT Of course, you had better make: CONTROL.BITBUCKET 255 characters wide to avoid lots of annoying truncation messages. 4.2. Can I edit SQL*Forms code with my text editor?

Yes, but it is unsupported (since IAG became SQL*Forms). Personally, I use the SQL*Forms Designer interface to cut the basic code and screen layout and then do the rest inside my text editor. I wonder how many others do it this way? Forms 2.3 is difficult because the syntax is so obtuse and takes a fair bit of mucking around if you want to learn how to change the logic. Just changing an SQL statement, however is easy enough. (I was able to do it because I grew up with SQL*Forms before it even had a screen painter or field triggers

or key triggers, so I learnt gradually). Forms 3 is a LOT easier, but be warned, DO NOT INCLUDE TABS. Use leading spaces. TURN OFF AUTOINDENT FEATURES OF YOUR EDITOR (or post-process with the expand utility of UNIX which converts tabs to spaces). Oracle proposed not having a human readable .inp file for SQL*Forms 4, but enough protests were received to prevent removal of this feature. If you are using a text editor, you must remember to reload the form back input the database using the iac program. You will have to remove it using "iac -d" first. One thing worth noting is the fact that the text file (and the database definition) permits association of prompt text to be associated with the field, and position above or to the left of the field, moving automatically when you edit the position of the field. You can also automatically have the prompt repeated in multi-row blocks. With the screen-based interface, the text is hard-coded into display of the form and is NOT associated with the field. Thus you must move TWO things, the field and the associated text. Why doesn’t Oracle support the full .inp capabilities? By the way, check out the advantages of using .inp files as referenced source, particularly version control mentioned near the end of this document. 4.3. Can I edit SQL*Forms code by updating the database?

Yes, but it is unsupported. In SQL*Forms 2.3, the tables being with "IAP", in 3.0, with "FORM". Quite often, when I change the name of a column or table, I use a form created with forms tables as the base tables of the blocks to update the database and then generate the new forms. Using these tables for reports can also be handy to compare the definition and consistency of columns and fields that use it as well as for technical documentation (such as "where is Such-and-such a table used?). One very useful thing to do is run a query that brings up fields based on the same column and use the "duplicate field" key to copy the help message quickly. This can be a *lot* faster than opening up all the forms under SQL*Forms designer, navigating a million menus and then doing heaps of typing. Where I have had the luxury of specifying an entire application where each column had a unique name, it was very easy to write scripts that updated datatypes, lengths and help from the table

definitions and comments stored in the main data dictionary (After I had run a report to see what my update was going to do). This gave me a high degree of confidence in the integrity of my application. Similar scripts made help consistent for fields across the entire application (I had a supplementary table that kept my help keyed on field name, this was used to update the forms database). Depending on how you set up forms, most users see tables like SYSTEM.FORM_APP, SYSTEM.FORM_BLK, etc. These contain code for forms owned by that user. If you are SYSTEM, then you can see tables SYSTEM.FORM_APP_, SYSTEM.FORM_BLK_, etc that have code for all users in them. 4.4. Why can't I see data in a control field?

If you have the Displayed attribute on for a field, that only means that the field is displayed, not the data. You need to turn on ECHO INPUT, even if the field is not to be entered by the user. 4.5. Why is my terminal scrambled in a user exit?

When running Oracle Forms, the line settings are all changed. Particularly whether the I/O is raw or cooked. If you are doing terminal I/O in a user exit you will need to save the settings, set them to what you want, do your stuff and then reset them. You can save settings with the UNIX shell command stty -g stty.save.file Restore settings using stty `cat stty.save.file` 4.6. What happens to LONGs?

LONGs are only partially supported in Forms 3. Anything after the 255th character goes to the great bit bucket in the sky. How to deal with LONGs using forms is to get the ROWID into a field in your form. Your user exit picks this up and selects from the base table using the ROWID, then breaks the LONG up into a number of forms fields. Rumor has it that Forms 4 will handle LONGs a lot better. 4.8. What are user-written form level functions? These are a specialized version of procedures not properly documented. They vary from procedures in that they keyword "function" is used, they must be declared with a return type and the keyword "return" is used within the code. A simple example is as follows: DEFINE PROCEDURE NAME = TO_FAHRENHEIT DEFINITION = <<<

function MY_FUNCTION ( VNAME in number ) return number is Begin Return ((VNAME * 9 / 5) + 32); end; ENDDEFINE PROCEDURE Within other code, it is used as follows: : f := TO_FAHRENHEIT (:c); Choosing to use a function over a procedure is a stylistic issue. I prefer to keep all arguments to functions read-only (i.e. declared as "in") and use them where I want to use the result in an expression a lot. I also use the word function for those procedures that return a simple value and do not really perform side effects. 4.9. How can I use regular expressions for field validation?

OK, you're probably a UNIX person asking this. For those of you that are not, regular expressions are a much more expressive way of specifying a "wildcard string", analogous to % and _ used with the "LIKE" keyword of SQL. For example [A-C]*T would match T, AT, CT, CAT, BAT, BBACACCACT. You need to write a C user exit that uses the sedstr () function. This permits both matching (and tells you the position of the match) or substitution (hence the name - "sed" on C strings). This is available from any comp.sources.unix archive. This also uses other PD code, the "regexp" package out of EMACS. You can get EMACS from any GNU archive. Of course, you could write the whole thing from scratch using the regexp routines provided straight from the C libraries, but sedstr() is *MUCH* easier to use. Novice C programmers can use sedstr (), they cannot use the standard regexp package. Both these archives are on archie.au in Australia, in ~ftp/gnu and ~ftp/usenet/comp.sources.unix. I think garbo in Europe and Simtel in the US also have this stuff. Contact your local archive server to find the site nearest you. 4.10. What is a user-exit? A user-exit is a routine in some other language (typically C or Pro*C) written locally and linked in to Oracle forms. When I say relinked, I mean create a new executable that includes your object (*.o) files. This *must* be managed by your DBA and thought out carefully, as your forms executable size will increase. Also, your code should be damn well behaved or you'll core dump everyone and be most unpopular. User exits are called from your PL/SQL and can be passed an argument as a bit fat string up to 255 chars. They can read and write forms fields using "get" and "put" functions.

It is thus a bad move to include application-specific code as user exits except where absolutely necessary. General purpose routines are another matter. Attributes of good candidates are (1) Good at something forms cannot do easily (2) Not suitable for V7 DBMS pipes. (Actually DBMS pipes are sort-of "kernel user-exits") Examples of good candidates include a) Getting data from non-Oracle sources: text files, other RDBMS b) Extra string routines such as regex type searches c) Dealing properly with LONGS d) Fancy mathematical functions e) Standard I/O via files and pipes f) Inter process communication: shmem, sockets, msgq, sems, etc. [Warning: Ad On] Actually I've written a few of these, along with the parsing of the single command argument into argc, **argv for you C Programmers. Cannot release it though as it is proprietary, although good deals negotiable with my lords and masters. [Ad Off] Proprietary). User-exits are good for things that are (1) not in sqlforms area of expertise and/or (2) to be done at the front end, not via V7 DBMS pipes. Good examples would be routines to perform regex searches, read data from non-Oracle sources, send

Inter-process communication messages routines to calculate Normal distribution stuff, read stuff from text files into fields.

4.10. How can I call a popup window for field validation?

OK, so you are trying to go to a popup window in your On-validate trigger and you cannot. Basically you cannot do "go(blk|fld) (blk|fld)name)" type things in most "on-", "pre-" and "post-" triggers. What you need to do is a. Write a procedure or function that does the to-and-froing. b. Call that function from all the appropriate "key-" triggers in that field context. You will need to check whether the field has changed, etc. Yep, it is ugly. Anyone got a better way? 5. SQL*FORMS 4 QUESTIONS -------------------------5.1. What new features can be expected in forms 4 generator from CASE?

Forms will be generated with support for forms 4 widgets such as push buttons, radio boxes, check boxes. GUI objects will follow layout preferences defined in the CASE dictionary. Client-server applications will be generated appropriately. 5.2. What new features can be expected in forms 4?

Full backward compatibility with SQL*Forms 3.0. If you have forms 2.3 code, this should be updated first to SQL*Forms 3 using iac30/iag30. Backward compatibility with SQL*Menu 5.0 is also supported. (SQL*Menu functionality is included in SQL*Forms 4). GUI objects (buttons, check boxes, radio buttons, images, dynamic boilerplate, etc) even in characters and block modes. Bitmap editor. Support for source in flat files. Better integration with other Oracle products (such as graphs, etc, embedded in a form). Shared modules: Some modules can be put into shared memory segments if you write a nice set of library functions and triggers. This cuts down the total memory requirements. 6. PRO*C QUESTIONS -------------------6.1. Why are my C variables overwritten?

This question only gets phrased this way once you've got to the stage of debugging your programs by putting printf() calls everywhere because you cannot figure out what is going on. It usually stems from the fact that you have been writing C for some time and are new to the Pro*C precompiler. The problem is that Pro*C does *not* understand the scoping of C variables in a file. Basically, if you have declared a variable to Pro*C in an EXEC SQL BEGIN DECLARE .... END DECLARE section, it is global to the file rather than limited to the C scoping you have declared it in. You also cannot use Pro*C to refer to the same variable in different files (i.e. the same part of memory, by declaring the variable to be extern in one file). Basically, except where necessary, it might be a good idea to limit a Pro*C source file to a single function, thus avoiding this sort of problem. This can pose a problem if you want to deal with varchar data from other files, as Pro*C does the declaration for you. You can pass the varchar across to other functions by pointers. 6.2. Can I use C preprocessor definitions for VARCHAR size?

Using Pro*C, you cannot - Pro*C has finished before the C preprocessor gets a look in and it won't accept a symbol. One way around is to write a set of C functions that deal with varchars and use these in functions that do not directly access the database. I have a suite of functions that create a varchar

library that permits such declarations, mallocs for varchars, as well as implementations of varchar versions of string.h type functions and conversions. You can mail me, or if I become overwhelmed, I will post it again to comp.databases.oracle. Another way using Pro*C is to DECLARE your Pro*C variables as pointers to varchar, and declaring the *real* storage in parts of the file not seen by Pro*C and using C preprocessor symbols. You can be quite evil to embedded SQL precompilers if you are wanting to get Oracle to return a maximum of n characters and not overwrite your n+1th null character and thus make C strings easy. Simply declare your C variables at the appropriate length to C rather than in a DECLARE section. To hold a 6 character string, you need seven bytes. Put the EXEC SQL DECLARE section inside C comments and make the size of the char to be 6, easy if you know that the column is char(6). Note that the EXEC keyword must NOT appear on the line in which the comment opens, but further down. E.g. /* Begin C comment This stuff not seen by C but still visible to Pro*C EXEC SQL BEGIN DECLARE SECTION; myvar char(6); EXEC SQL END DECLARE SECTION; End of C comment */ char myvar[7] = { 0,0,0,0,0,0,0 } ; Note that Pro*C then assumes it is binding a 6-byte char field, C has got 7 bytes, which you set to all null (0x) characters and you can get data in and out quickly as Oracle will only take or put 6 characters, but C functions like strcmp() will not runaway as the 7th byte has a null terminating character.

Unless you hide the SQL declarations from C, you will get duplicate definition errors, which is why you DECLARE within C comments.

Definitely not supported but can make life much easier. It is also the nicest perversion of a language facility that I ever cooked up. This trick was first developed for the Ingress esqlc precompiler. Have not tried it for a while - I use my varchar handling library to deal with varchars and I do not risk getting into trouble should the next release of Pro*C get the smarts to know if it is commented out. Let me know if you find it to work. 6.3. What can I do about "line too long" errors with version control?

Version control systems usually substitute a symbol in your original code with a longer expansion. For example, in RCS, you can have the keyword Id that expands to include the filename, author, date, etc. As Pro*C is at least slightly brain-damaged in not being able to handle long lines (partially fixed by a Command-line option that ups the limit a bit), you should be careful of this and use separate version control key words on different lines, e.g. the filename, author and version number keywords should be kept separate.

You can also make it safer by using a variable in your make files (or equivalent), PROC, defined to include the appropriate command line switches you commonly use, including the one to set input and output line lengths to the maximum. 6.4. Why do my compiles crash or weird things happen?

Sometimes your C compiler does not obey the System V way of doingthings. This happens in BSD derived versions of Unix (like SunOS) and VMS. Basically if there is an option available to use System V compatibility on your gear, then those options should be used when

working with Pro*C. See similar question in UNIX QUESTIONS section.

If you have a "dual universe" machine, like Pyramids and some others, make sure you do your C compilation in the AT&T System V environment. 6.5. Can I use C++? Pro*C is not designed for C++. You can of course use the OCI (the

Oracle C Interface) in C++ and link in the appropriate libraries as you do not have to pass your code through the Pro*C precompiler.If you *do* want to use C++ with embedded SQL, then what you should do is write a "wraparound" C function in Pro*C and call this from your C++ code where appropriate. Be careful, however, because not all the code produced from Pro*C is suitable as re-entrant code.

I believe that a third party has an SQL*C++ product available, but I have no details as yet. 6.6. How do I use OPS$login? Use "/" for the username/password combination 7. CASE QUESTIONS ------------------ 7.1. Can CASE generate forms with owner prepended to table names? Set the TABOWN option. 7.2. Can CASE generate V7 databases? CASE 5.1 is needed to take full advantage of V7 constructs from within CASE. 8. UNIX QUESTIONS ------------------ 8.1. Can I create a compressed export on the fly without needing to have the space for both the export file and the compressed file?

Yes, use named pipes. mknod p myexport.dmp # Make the pipe compress < myexport.dmp myexport.dmp.Z & # Background compress Export scott/tiger filename=myexport.dmp # Do export The only space you need is that for the final compressed file

and about 4 disk blocks for the pipe. This is because if the pipe is full (compress might be slower than export), the writing process is blocked until the pipe empties a bit. The result is very efficient with disk. You can do a similar thing the other way to import the file. 8.2. How can I prevent trailing spaces in a spooled report? You can't. Post-process with sed: sed -e 's/ *$//' < infile outfile This problem affects other OS versions as well. For VMS, you would have to write a DCL script that fiddles with SYS$INPUT and SYS$OUTPUT and uses LEXICALS to trim the lines. Don't ask me for details - my VMS is rusty and I do not have a manual handy. Could someone mail me (directly) the DCL and I'll include it here and move the question to SQL*Plus. 8.3. How can I get an environmental variable into SQL*Plus variables?

a. Create a sequence accessed in glogin.sql (e.g. my_seq) This permits you to have a "unique" number to build a file that will not conflict with another process. Column x old_value tmp_num noprint; Set heading off Set pause off Select my_seq.newvalue x from dual; b. Create a getenv.sql script like the following host echo "define &1=\"$&1\"" $HOME/s&&tmp_num..sql start $HOME/s&&tmp_num..sql host rm $HOME/s&&tmp_num..sql

c. When you want to create a variable "LOGNAME" that reflects the LOGNAME environment variable, do the following start getenv.sql LOGNAME OK, so it is a bit resource heavy, and may need to be altered for your implementation, but you should get the basic idea. Of course, SQL variables are NOT case sensitive.... Other operating systems can do a similar thing, I would expect, but not necessarily so easily. Under VMS, for example, I had to write a C program that did a getenv(3C) and then produced the Sqlplus script file that had the define in it. However, because of the process model of VMS, it was much too slow apart from the most important variables. Maybe let the C program take multiple arguments and produce a line for each. 8.4. Can I pipe stuff through SQL*Plus?

Yes. For example in vi, I often need to reference a table structure. I simply type "desc EMP" into a new line in my

buffer, :.,.!Sqlplus -s / and wait for the employee table description to appear, which then gets cut and pasted into the SQL statement I want. Piping through grep is handy, as is through sed or even awk for formatting. Seriously though, get Oraperl. 8.5. Why does Pro*C compiles or programs crash on my Sun?

Some Background --------------- SunOS 4.x (a.k.a. Solaris 1) is a BSD based OS. It comes with two C compilers. One is in /usr/bin/cc (which should be linked to /bin/cc) and it the BSD compiler, pointing to BSD header files and libraries. The other is in /usr/5bin/cc (which should be linked to /5bin/cc) and points to AT&T System V headers and libraries. You may have GNU C installed on your system. Note that Solaris 2 is System V-based. SunOS 4.1 comes standard with TWO C Compilers. /bin/cc The BSD based compiler Gets default includes and libraries from /usr/include and /usr/lib /5bin/cc The AT&T compiler Gets default includes and libraries from /usr/5include and /usr/5lib You may also have GNU C installed on your system. This too is based upon BSD. The BSD and AT&T compilers use libraries and include files from different directories, reflecting the system libraries of the two

different dialects of UNIX. Sometimes the function is just called under another name, sometimes the number of parameters (and their

ordering) is different. Examples include Get working directory getcwd vs. getwd Copy Memory memcpy vs bcopy Compare Memory memcmp vs bcmp Oracle Pro*C libraries call System V library functions if one is

Commonly available for your architecture. Obviously, if the Oracle libraries have references to the System V version, they will either be unresolved in the BSD libraries, or worse, resolve to something inappropriate.

What to Do ---------- Oracle recommends that when using Pro*C (or even installing and

linking Oracle) you have the /5bin directory ahead of /bin in your PATH variable. [This is good practice anyway, because you will get used to the

System V versions of commands (df and ps are good examples of this - I usually create a soft link to /bin/ps and /bin/df as /usr/local/bin/bps and /usr/local/bin/bdf - a similar practice to

HP when they supply both versions of a utility). ] You might like to try the following if you *really* want to use the GNU C (or other BSD) compiler. (1) Using GNU C, but point at System V libraries (2) Using GNU C and libraries but add in your own, written in GNU C that mimic the system V calls. You'll know which ones you need, as they will be the unresolved references. Some of these may simply be stubs that call the BSD function of a different name or reorder the parameters. (3) Extract the functions you need from the System V libraries and add them to your list to be linked in via the make file. When working in the Oracle environment (or simply to help you change to a System V frame of mind), you should put the System V directories ahead of the BSD directories in your PATH. Also, the CC variable (especially in your Makefiles) should point to the System V compiler. Alternatively, you can try using the -I /5include and -L /5lib flags ahead of other directories. (These are probably linked from /usr/5include and /usr/5lib).

Look, I know it involves some hacking, but if you are that keen on Gnu C and only using your products in-house, you should be OK. I am not knocking Gnu C, mind you. Gnu C is a must for many shops developing in-house code and compiling things from the net. One R&D shop I worked in tried it out on our code, and it gave tighter executables than the native HP compiler at the time!

One other thing to note if you are running Solaris 2 is that the good C compiler has been unbundled. The compiler that comes standard with Suns now is reported by some to be dain bramaged. If you are serious about your compiler (and you should be if you are running Oracle) then spend the money and get the *REAL* developers kit. (At least this is not as bad as some UNIX systems distributed without a compiler!) 8.5. How can I find a lost Oracle export file?

You need to add a description of the layout of an export file tothe /etc/magic file. See magic (4) and file (1) for details. Use

the fact that an Oracle export starts with a control-A and then the word EXPORT and the version number of the export that

produced it. (Use the string (1) or od (1) command to check this out). Your system administrator can then edit /etc/magic to not Only recognize an export file but tell you the version number when you use file(1). Say the key description was "Oracle Export", you can look for Oracle export files from the current directory and below as follows: find . -type f -exec file {} \; | grep "Oracle Export" | \ sed -e 's/:.*//' 8.6. How can I tell make about SQL*Forms?

I use a make include file $ORACLE_HOME/local/include/oracle.mk. Among other things it sets up the following: OUP = / # Oracle user/password, defaults to OPS$login IAG = iag30 # Generates .frm from .inp IAC = iac30 # Converts b/w FORM_% tables and .inp

# I use .dbo to sign a form out of database, and .dbi as a sign-in . SUFFIXES: .inp .frm .dbo .dbi . Inp.frm: - rm $*.frm $*.erf - $(IAG) $* $(OUP) $*. inp.err 2&1 test $*.frm . inp.dbi: - rm $*.frm $*.erf - $(IAG) $* $(OUP) $*. inp.err 2&1 test $*.frm - $(IAC) -d $* $* $(OUP) $(IAC) -i $* $* $(OUP) touch $*.dbi . dbo.inp: - mv $*.inp $*.inp.bak $(IAC) $* $* $(OUP) - touch $*.dbo touch $*.inp 9. MISC QUESTIONS ------------------9.1. How can I alter table storage parameters from an export file?

Use the undocumented INDEXFILE=xxxxx parameter. This creates an ASCII file "xxxxx" with the table creation statements REMmed out and the index creation statements not. Edit this to change the table storage parameters (such as initial size, tablespace, etc). Example: imp scott/tiger filename=myexport.dmp indexfile=myexport.sql BTW, it IS documented in V7. 9.2. What makes the best Oracle server for a network?

OK, I am biased and will say get a Sun. Even the low-end SPARClassic might service around 32 concurrent users, but you are limiting your upgradeability. A SPARC-10 is probably the best Option for mid-range stuff for the long term. If you are pushing departmental servers (users pushing the 100 mark and above) consider the SPARCserver 1000 series. There is some justification for this, Oracle do most of their development on Suns, more Oracle licences go onto Suns than anything else and so releases will be timely and well supported. Also, as the most important source of revenue for Oracle is UNIX

based, going UNIX for the server is pretty sensible. Actually, Oracle and Sun get to look at each other's source code at early development levels and are HEAVILY allied against the common enemy, a.k.a Bill Gates. Talk is that Oracle and Sun is about to release benchmarks using Oracle V7 and Sun's Solaris 2.1 that will show very good bang for buck compared to anything else. The other thing is that Sun's Solaris 2.2 is rumored to have RAID and Journalled File Systems, making it virtually OK to kick out the power supply without too much drama. This combined with Oracle DBA tools makes a pretty good fault tolerant machine. With Netware (Novell) and WABI (run Windows binaries) facilities available or bundled, it is a pretty attractive machine. In the mid-range, I do think I should at least mention HP and Sequent. Certainly I have never had any problems with HP kit or service. For low end users, even though a Novell, or OS/2 server might look cheaper, I do think that UNIX makes a better architecture for something as complex as a multi-user database to live in. Unless, of course, rumors of Novell bundling Oracle sometime in the future are true and the price becomes impossible to resist. The (apparent) lack of Virtual Memory in Novell means the Oracle server could run out of memory and blow up. Windows NT could be interesting. It promises heaps of features, but on looking recently at the "system calls" for Windows I balked at the loss of clean elegance at UNIX structures. Perhaps Windows NT will be just as threatening. [What platform does NT perform best on? A 35mm slide projector :-)] Its chief designer, an ex-DEC SE, however, does deserve respect tho. 9.3. How can I implement version control? The issue of version control for Oracle applications code is a sticky one and is complicated by issues of different operating systems, but most especially by Oracle's predilection for Non-ASCII storage formats. Note the ruckus caused when Oracle proposed no ASCII .inp format file for Forms4. Version control is an important issue for MIS departments however

and MUST be successfully addressed, otherwise things start falling apart.

1. Choice of Version Control Tool ---------------------------------- There are a number of version control tools available for different platforms. These include CMS for VAX/VMS and SCCS for AT&T UNIX. In the MS-DOS world, most formats are proprietary. Our choice of tool was RCS however, because of the following reasons

a. Reports and management are more user friendly than SCCS, the default tool for UNIX, our main development platform (although our network includes DOS and VMS nodes). b. Source code is available in the public domain from most sites archiving GNU code. This makes it possible to port it fairly easily, especially if you are running VAX/VMS and have either the POSIX C libraries or using GNU C. DOS source code and binaries are also available. We can also modify the way some of the programs (particularly the report programs) work to perform extra things we like. c. The binary files used to store initial code and deltas (from which any version can be retrieved) are compatible across architectures. For example, I can use the DOS RCS programs to extract source files from the binary RCS files transferred from the UNIX machine. d. An add-on, CVS, also available in the public domain, permits fairly easy management where TWO sites are carrying out concurrent development. This is common where a vendor is providing the source, but some local changes are being made. e. Perusal of Oracle source code for scripts and the like shows that they use RCS. If it's good enough for them to use PD products ..... f. RCS is more efficient than the System V standard SCCS. SCCS stored the original intact and then the deltas. RCS stores the most recent intact and then the deltas. Getting more recent files is thus easier with RCS. g. RCS permits you to "remove" intermediate versions (e.g.

between 7.2 and 7.5 when you are on 9.1) when required.SCCS cannot.

2. Outline of RCS operation ---------------------------- Essentially, you check in a file to RCS (with optional security information, "aliases" for the version and state information). Subsequent check ins are stored as deltas within the RCS storage file, (unless you are checking in binary files, in which case the entire new copy is stored). For ASCII files, RCS looks for certain keywords, and on check out, substitutes the version specific information. These keywords are enclosed between dollar signs. These keywords include RCSfile filename without path Header Combination of the keywords below Author The user name of the file owner Source Full path/filename of source Date Date and time of check in State A keyword you can assign e.g. "Cut", "Tested", etc

Id A combination of all information (Dangerous for many Oracle products) You should be able to see expanded versions of these near the top of this file. I have not used the dollar signs here as they would get expanded and ruin the format. You can also cause RCS to include in your source all comments made specific to that version, for example, the reason why changes had to be made using the Log keyword. Note that with ASCII files, only storage for the changes between successive versions are required. For binary files, the entire file is stored - chewing up disk fairly quickly. Various RCS utilities allow you to extract any version, merge changes from different branches and see the differences between any two versions. Versions for multi-user operating systems allow better control than the native operating system, as you can assign a list of users authorized to manipulate the files. Authorized users can be different for each file. 3. Basic Philosophy of Version Control with Oracle App Source -------------------------------------------------------------- Wherever possible, use version control on ASCII representations of the code. Thus for forms, use the .inp file, for menus, the .sql file produced by "exporting" the menu. For SQL*Reports, .rex files rather than .rep files are put under version control. The keywords are placed in the source, however you like, the ASCII file produced checked in to RCS. When moving to a testing or production environment, the source is checked out of RCS (resulting in keyword substitution) and "compiled" in the target environment to produce the runtime application. 4. General Caveat ------------------ Where source code for an Oracle application can be stored in the database (such as forms or menu), keyword expansion of the Id keyword can be dangerous, as it may expand to MORE than the database allows to be stored. Thus, rather than use Id, I use the more atomic keywords on different lines, these being unlikely to expand above legal limits. 5. Specifics for some products ------------------------------- A .SQL*Plus Scripts RCS keywords are generally placed in Remark lines B. SQL*Forms RCS keywords are placed in the comments at forms level. Selected keywords are placed as default values for Non-enterable fields, so that the user can see version

information. C. SQL*Menu RCS keywords are placed either in the title section of a menu or in the default value for a parameter, depending on how we want to use the keyword. If you do not want to do this, put a wraparound function to create the Remark line(s) at the top of the .sql file prior to checking it in. This will NOT affect Compilation of the resulting .dmm. D. SQL*ReportWriter Major BUMMER, .rex files are not "sensible" ASCII that will permit expansion of RCS keywords. The only way I know how to solve this is to version an ASCII file produced by selecting the data out of the report writer internal tables and versioning that, then using SQL*Loader to put them back into the SQL*ReportWriter tables in the production environment. While this would work, I have not tried it myself (as we do not use RW), but apparently some group in the US has a tool that performs this task. If anyone knows how I can contact that group, let me know please. Notes:

1. RCS and CVS, together with the GNU compiler you may need are available from most GNU archive sites. If you are in

Australia, try archie.au in ~ftp/gnu. Less up-to-date versions are also available in comp.sources.unix.

2. DOS RCS executables are available from SIMTEL. Again, in Australia, try archie.au (somewhere under ~ftp/micros/pc/oak, I forget which subdirectory).

3. I think I have seen OS/2 versions of RCS floating around.You could probably get the DOS patches and compile it for the OS/2 environment with a few mods anyway.

9.3. What books are available about Oracle?

First of all, I must mention the range of books produced by Oracle. You might not get the ones you need simply by ordering

the manuals for the products you buy. For example, there are quite a few books written by the Oracle UK team that are excellent, especially "Advanced SQL*Forms Techniques" and various CASE references (well Oracle UK was originally an independent group that created CASE, then known as SDD). Also look out for the Oracle Performance Tuning Guide. Some of the "Oracle UK" books are published independently by Addison-Wesley and written by Richard Barker and Cliff Longman. Note that Oracle have a whole book that lists technical publications available from them. This is worth getting.

Other books include: 1. Oracle Tuning beyond The Manual Peter Corrigan and Mark Gurry

Covers Oracle performance from design, DBA and application programmer perspectives. This book has been recommended by a number of people, and having worked with Mark briefly in 1988, I can tell you that he is no idiot. The thing to remember about this book is that there are about to be two versions of it. The first has been published by the authors themselves for A$69. (52 Rowena Parade, Richmond, Melbourne, Vic, Australia or mag@scammell.ecos.tne.oz.au). The second version is to be made available by O'Reilly and Associates in Sep 93 and is probably to be called "Oracle Performance Tuning". According to Mark, there has been almost a complete re-write together with the O'Reilly editors and it is now at the final review stage. While there have been a number of typos introduced by the rewrite which are currently being addressed, Mark seems to think that the result is a much more readable book than the original version. O'Reilly are sending me a review copy (thanks!) so expect more details in upcoming issues. 2. Mastering Oracle V6 Daniel Cronin and Joe Lee Provides a good overview of V6 application development in one handy book with an almost complete application used as an example. This book came out very soon after The release of V6 and thus only discusses Forms 2.3 and has a V5 to V6 migration guide. Not really detailed enough for power programming, does not go into Pro*XXX languages, but great for somebody just moving into RDBMS or Oracle. It would be nice to see a new edition for V7. 3. ?????? George Koch Have not seen this book, but has generally received favorable reviews. Apparently the V7 stuff seems tacked on to the end. 4. Dan's Oracle7 Guide Daniel B. Bikle I've put this here, because I think Dan will be marketing this, though some drafts are available from him gratis. He is building an ASCII file of tips and example code that can be cut and pasted into your code. I've seen early drafts and it looks useful. Dan is an Ex-Oracle employee and can be contacted via dbikle@alumni.caltech.edu and US phone 415/854-9542. New Questions

10.1 What is Library Cache Locks

When a database object (such as a table, view, procedure, function, package, package body, trigger, index, cluster, or synonym) is referenced

during parsing or compiling of a structured query language (SQL), (Data Manipulation Language (DML) or Data Definition Language (DDL), PL/SQL, or Java statement, the process parsing or compiling the statement acquires the library cache lock in the correct mode. In Oracle9i, the lock is held only until the parse or compilation completes (for the duration of the parse call).

Oracle: Frequently Asked Questions --------------------------------------------------------------------------------

What built-in functions/operators are available for manipulating strings? Can I print inside a PL/SQL program? Is it possible to write a PL/SQL procedure that takes a table name as input and does something with that table? What is the correct syntax for ordering query results by row-type objects? How do I kill long-running queries in sqlplus, Pro*C, and JDBC? In Pro*C, why do I get a strange "break outside loop or switch" error message?

--------------------------------------------------------------------------------What built-in functions/operators are available for manipulating strings?The most useful ones are LENGTH, SUBSTR, INSTR, and ||: LENGTH (str) returns the length of str in characters. SUBSTR (str,m,n) returns a portion of str, beginning at character m, n characters long. If n is omitted, all characters to the end of str will be returned. INSTR (str1,str2,n,m) searches str1 beginning with its n-th character for the m-th occurrence of str2 and returns the position of the character in str1 that is the first character of this occurrence. str1 || str2 returns the concatenation of str1 and str2. The example below shows how to convert a string name of the format 'last, first' into the format 'first last': SUBSTR (name, INSTR (name,',',1,1)+2) || ' ' || SUBSTR (name, 1, INSTR (name,',',1,1)-1)For case-insensitive comparisons, first convert both strings to all upper case using Oracle's built-in function upper() (or all lower case using lower()).

--------------------------------------------------------------------------------Can I print inside a PL/SQL program?Strictly speaking PL/SQL doesn't currently support I/O. But, there is a standard package DBMS_OUTPUT that lets you do the trick. Here is an example: -- create the procedureCREATE PROCEDURE nothing ASBEGIN DBMS_OUTPUT.PUT_LINE('I did nothing'); -- use TO_CHAR to convert variables/columns -- to printable stringsEND;.RUN;-- set output on; otherwise you won't see anythingSET SERVEROUTPUT ON;-- invoke the procedureBEGIN

nothing;END;.RUN;Then you should see "I did nothing" printed on your screen. DBMS_OUTPUT is very useful for debugging PL/SQL programs. However, if you print too much, the output buffer will overflow (the default buffer size is 2KB). In that case, you can set the buffer size to a larger value, e.g.:

BEGIN DBMS_OUTPUT.ENABLE(10000); nothing;END;.RUN;

--------------------------------------------------------------------------------Is it possible to write a PL/SQL procedure that takes a table name as input and does something with that table?For pure PL/SQL, the answer is no, because Oracle has to know the schema of the table in order to compile the PL/SQL procedure. However, Oracle provides a package called DBMS_SQL, which allows PL/SQL to execute SQL DML as well as DDL dynamically at run time. For example, when called, the following stored procedure drops a specified database table: CREATE PROCEDURE drop_table (table_name IN VARCHAR2) AS cid INTEGER;BEGIN -- open new cursor and return cursor ID cid := DBMS_SQL.OPEN_CURSOR; -- parse and immediately execute dynamic SQL statement -- built by concatenating table name to DROP TABLE command DBMS_SQL.PARSE(cid, 'DROP TABLE ' || table_name, dbms_sql.v7); -- close cursor DBMS_SQL.CLOSE_CURSOR(cid);EXCEPTION -- if an exception is raised, close cursor before exiting WHEN OTHERS THEN DBMS_SQL.CLOSE_CURSOR(cid); -- reraise the exception RAISE;END drop_table;.RUN;

--------------------------------------------------------------------------------What is the correct syntax for ordering query results by row-type objects?As a concrete example, suppose we have defined an object type PersonType with an ORDER MEMBER FUNCTION, and we have created a table Person of PersonType objects. Suppose you want to list all PersonType objects in Person in order. You'd probably expect the following to work: SELECT * FROM Person p ORDER BY p;But it doesn't. Somehow, Oracle cannot figure out that you are ordering PersonType objects. Here is a hack that works: SELECT * FROM Person p ORDER BY DEREF(REF(p));

--------------------------------------------------------------------------------How do I kill long-running queries in sqlplus, Pro*C, and JDBC?Sometimes it is necessary to stop long-running queries, either because they take longer to run than you'd like, or because you realize you've made a mistake. It is important kill off such queries properly so that they don't take up extra computational resources and prevent others from using the system, especially near project deadlines when resources are most strained. As a general precautionary measure, please be sure to test your queries under sqlplus prompt before running them through CGI or JDBC. It is much easier to kill a query in sqlplus than in CGI or JDBC. If your test query takes a long time to run under sqlplus, you can simply hit Ctrl-C to terminate it.

Never close an ssh or telnet or xterm window without properly logging out. Always quit your programs (including sqlplus), stop Java servlets, and type "exit" or "logout" to quit. If you force-close your ssh/telnet/xterm window, there may still be processes running in the background, and you may be taking up system resources without knowing it.

If, for some reason, you cannot logout normally (for example, the system is not responding), you should open another window, login to the same machine where you have the problem, and kill the processes that is causing trouble:

Type "ps -aef | grep [username]" to find the Process IDs of your processes (replace [username] with your leland user name), and kill the processes you want to terminate using "kill [processID]". Always use the "kill" command without the -9 flag first. Use -9 flag only if you cannot kill it otherwise.If you closed the window by mistake and do not remember which sweet hall machine you were logged into, open another window immediately and log into any sweet hall machine, then type "sweetfinger [username]" (replace [username] with your actual leland user name). It will give you the machine names you were on a few minutes ago. Then, log in to the appropriate machine and kill your processes there. If you issued a query through JDBC that is taking a long time to execute and you want to kill it, you should stop your Java servlet. In most cases this will kill the query. You can also use the setQueryTimeout([time in seconds]) method on a statement object to stop queries that run too long.

If you issued a query through CGI that is taking a long time to execute, normally the CGI service will kill it for you within 10 seconds. However, the above occasionally fails to work, and we do not know of any better way of killing runaway queries issued by JDBC or CGI (other than asking the administrator to kill them for you). That's why we ask you to always test your queries under sqlplus first. It is much easier to kill queries there.

--------------------------------------------------------------------------------In Pro*C, why do I get a strange "break outside loop or switch" error message?If you get an error message "break" outside loop or switch

when compiling your Pro*C program, chances that you have the following statement somewhere before a loop:

EXEC SQL WHENEVER NOT FOUND DO break;

After the loop, you should insert the following statement:

EXEC SQL WHENEVER NOT FOUND CONTINUE;

This would cancel the previous WHENEVER statement. If you do not do this, you may get the error message at subsequent SQL calls.

Oracle Faq’s

"Oracle 8i is what type of database?","A) hierarchical networkB) object networkC) hierarchical relationalD) object relational","D) object relational""Which two (if any) of the following three WHERE clauses are equivilent. (Note - the numbers are for reference only, they are not part of the WHERE clauses)1 WHERE ename = 'SMITH'2 WHERE UPPER(ename) = 'smith'3 WHERE ename = UPPER('smith')","A) 1 and 2B) 1 and 3C) 2 and 3D) each will yield different results","B) 1 and 3""Which keyword is used to suppress duplicate rows from being displayed?","A) SUPPRESSB) DISTINCTC) UNIQUED) NONDUPLICATE","B) DISTINCT""A primary key can be made up of","A) one columnB) two columnsC) three or more columnsD) A, B, or CE) None of the above","D) A, B, or C""Which of the following Oracle versions meets ANSI standards?","A) SQL*PlusB) PL/SQLC) SQLD) ISO","C) SQL""Which of the following is not a PL/SQL section?","A) LOOPB) EXCEPTIONC) DECLARED) BEGIN","A) LOOP""Which of the following does have a semi-colon at the end?","A) A FROM clause which is followed by a WHERE clauseB) The keyword END at the end of a PL/SQL blockC) The keyword DECLARE at the beginning of a PL/SQL blockD) A SELECT clause","B) The keyword END at the end of a PL/SQL block""Which was the first object-capable database developed by Oracle?","A) Oracle 5.2B) Oracle 7C) Oracle 8D) Oracle 8i","C) Oracle 8""Which of the following is not a component of the relational model?","A) random file capability on DASDB) collections of objects or relations that store dataC) a set of operators that act on the relations to produce other relationsD) data integrity for accuracy and consistency","A) random file capability on DASD""Which of the following is not a key component of the ER model?","A) entitiesB) hierarchiesC) attributesD) relationships","B) hierarchies"

"Which of the following is a DML statement?","A) SELECTB) COMMITC) UPDATED) DROP","C) UPDATE""Which of the following is not a DML statement?","A) SELECTB) INSERTC) DELETED) UPDATE","A) SELECT""Which constraint is displayed via the DESCRIBE command?","A) UNIQUE KEYB) CHECKC) PRIMARY KEYD) NOT NULL","D) NOT NULL""Which of the following is a DML statement?","A) CREATEB) COMMITC) INSERTD) DROP","C) INSERT""Which SQL*Plus command is equivalent to START?","A) @B) $C) !D) (+)","A) @""Which of the following is a DML statement?","A) CREATEB) TRUNCATEC) ROLLBACKD) DELETE","D) DELETE""A field is defined in Oracle as the intersection of what?","A) attribute and tableB) select and fromC) data type and PL/SQLD) row and column","D) row and column""Which of the following is a DDL statement?","A) GRANTB) COMMITC) DELETED) CREATE","D) CREATE""Which of the following is not a DDL statement?","A) ALTERB) INSERTC) RENAMED) DROP","B) INSERT""How many keywords are there in the following? SELECT ename, sal, hiredate FROM emp WHERE deptno = '10' ORDER BY ename;","A) 1B) 2C) 3D) 4E) 5F) 6","E) 5""How many clauses are there in the following? SELECT ename, sal, hiredate FROM emp ORDER BY ename;","A) 1B) 2C) 3D) 4E) 5F) 6","C) 3""How many statements are there in the following?

SELECT ename, sal, hiredate FROM emp WHERE deptno = 10 AND empno > 7900 ORDER BY ename;","A) 1B) 2C) 3D) 4E) 5F) 6","A) 1""A relational database can contain at most one table.","True/False","False""A given table can many rows.","True/False","True""SQL keywords are case sensitive.","True/False","False""PL/SQL is the ANSI created language for SQL systems.","True/False","False""Commands within SQL*Plus can be abbreviated.","True/False","True""A column is made up of many rows, and rows are made up of many tables.","True/False","False""A column which serves as the primary key for a table can have duplicate values if the constraint UNIQUE VALUE is set to NULL.","True/False","False""A primary key can not contain any null values.","True/False","True""Keywords within SQL can be abbreviated.","True/False","False""A column which has the UNIQUE KEY constraint will have an index created for it automatically.","True/False","True""A column which has the UNIQUE KEY constraint can contain NULL values.","True/False","True""What does 'ER' stand for, as in 'ER Modeling'?","Short Answer","Entity Relationship""Two tables can be related via their common column. In one table this column would be the Primary Key. What term describes the related column in the other table?","Short Answer","Foreign Key""What does SQL stand for?","Short Answer","Structured Query Language""What does PL/SQL stand for?","Short Answer","Procedural Language/SQL""What does ANSI stand for?","Short Answer","American National Standards Institute""What does ISO stand for?","Short Answer","International Standards Organization""List the three (3) DML statements. Also, what does DML stand for?","Short Answer","INSERTUPDATEDELETE

Data Manipulation Language""List the five (5) DDL statements. Also, what does DDL stand for?","Short Answer","CREATEALTERDROPRENAMETRUNCATE

Data Definition Language""List the three (3) Transaction control statements.","Short Answer","COMMITROLLBACKSAVEPOINT""List the two (2) DCL statements. Also, what does DCL stand for?","Short Answer","GRANTREVOKE

Data Control Language""What is the term used to describe a primary key which is composed of two or more columns.","Short Answer","Concatenated"

"The standard with which Oracle's version of SQL complies with.","A) ASCIIB) ANSIC) NHTSAD) ISO","B) ANSI""Write a statement to retrieve all columns from the emp table.","Short Answer","SELECT *FROM emp;""Write a statement to retrieve employees who make more than 2000 in salary, listing their name and salary.","Short Answer","SELECT ename, salFROM empWHERE sal > 2000;""Write a statement to retrieve employees who work in Dallas.","Short Answer","SELECT e.ename, e.deptno, d.locFROM emp e, dept dWHERE e.deptno = d.deptnoAND d.loc = 'DALLAS';""Write a statement to retrieve the average salary for all employees.","Short Answer","SELECT avg(sal)FROM emp;""Write a statement to retrieve the average salary for all employees who are NOT salesmen.","Short Answer","SELECT avg(sal)FROM empWHERE job != 'SALESMAN';

-also-

SELECT avg(sal)FROM empWHERE job <> 'SALESMAN';""Write a statement to retrieve employees' name and salary for those who earn less than the average for all employees.","Short Answer","SELECT ename, salFROM empWHERE sal < (SELECT avg(sal) FROM emp);""Write a statement to retrieve the ename and loc for all employees, plus sort the data by loc ascending, then within loc by ename descending.","Short Answer","SELECT ename, locFROM emp e, dept dWHERE e.deptno = d.deptnoORDER BY loc, ename DESC;""Write a statement to display the number of employees at each location (New York, Dallas, Chicago, and Boston).","Short Answer","SELECT loc, count(*)FROM emp e, dept dWHERE e.deptno = d.deptnoGROUP BY loc;""The LINE_ITEM table contains these columns LINE_ITEM_ID NUMBER(9) Primary Key ORDER_ID NUMBER(9) PRODUCT_ID VARCHAR2(9) QUANTITY NUMBER(5)

Evaluate this SQL statement: SELECT quantity, product_id FROM line_item ORDER BY quantity, product_id

Which statement is true concerning the results of executing this statement?","A) The results are sorted numerically only.

B) The results are sorted alphabetically only.

C) The results are sorted numerically and then alphabetically.

D) The results are sorted alphabetically and then numerically.","C""Which syntax turns an existing constraint on?","A)ALTER TABLE table_nameENABLE contstraint_name;

B)ALTER TABLE table_nameSTATUS = ENABLE CONSTRAINT constraint_name;

C)ALTER TABLE table_nameENABLE CONSTRAINT constraint_name;

D)ALTER TABLE table_nameSTATUS ENABLE CONSTRAINT constraint_name;

E)ALTER TABLE table_nameTURN ON CONSTRAINT constraint_name;","C""The EMPLOYEES table contains these columns: LAST_NAME VARCHAR2 (25) SALARY NUMBER (6,2) COMMISSION_PCT NUMBER (6)

You need to write a query that will produce these results: 1. Display the salary multiplied by the commission_pct. 2. Exclude employees with a zero commission_pct. 3. Display a zero for employees with a null commission value.

Evaluate the SQL statement:

SELECT last_name, salary * commission_pct FROM employees WHERE commission_pct IS NOT NULL;

What does the statement provide?","A) All of the desired results

B) Two of the desired results

C) One of the desired results

D) An error statement","C""Which SELECT statement should you use to extract the year from the system date and display it in the format '1998'?","A)SELECT TO_CHAR(SYSDATE, 'yyyy')FROM dual;

B)SELECT TO_DATE(SYSDATE, 'yyyy')FROM dual;

C)

SELECT DECODE(SUBSTR(SYSDATE, 8), 'YYYY')FROM dual;

D)SELECT DECODE(SUBSTR(SYSDATE, 8), 'year')FROM dual;

E)SELECT TO_CHAR(SUBSTR(SYSDATE, 8, 2), 'yyyy')FROM dual;","A""Which of the following correctly describes the precedence of mathematical operators?","A) Multiplication, Division, Addition, SubtractionB) Subtraction, Division, Addition, MultiplicationC) Multiplication, Addition, Division, SubtractionD) Subtraction, Division, Addition, Multiplication","A""Which of the following correctly describes the precedence of comparison and logical operators?","A) And, Not, All comparison operators, OrB) Not, And, Or, All comparison operatorsC) All comparision operators, Not, And, OrD) All comparison operators, Or, Not, And","C""For a hire date of December 10, 1999, what does the following function evaluate to?

TO_CHAR(hiredate, 'fmDD MONTH YYYY')","A) December 10, 1999B) 10 December 1999C) 12/10/1999D) Tuesday, December 10, 1999E) Ten DECEMBER 1999F) 10 december 1999G) Ten December 1999","B""For the clauses GROUP BY, HAVING, and WHERE, what is the correct order of evaluation? ","A) Where, Group By, HavingB) Group By, Having, WhereC) Having, Where, Group ByD) Where, Having, Group By","A""Which of the following SQL*Plus commands reads in User Input and stores it in a variable?","A) DefineB) VariableC) ColumnD) Accept","D""Which of the following is NOT true of DML?","A) It is executed when you add new rows to a table.

B) It is executed when you modify existing rows in a table.

C) It is executed when you remove existing rows from a table.

D) It is executed when you select rows from a table.","D""Which of the following is the correct format for a SELECT statement which should select all columns in the emp table and be immediately executed?","A)SELECT *FROM emp/

B)SELECT *FROM emp;

C)SELECT all

FROM emp;

D)SELECT */FROM emp

E)SELECT &&FROM emp/","B""Which of the following is the correct format to clear a column?","A)CLEAR COLUMN column_name

B)COLUMN column_name CLEAR

C)DELETE COLUMN column_name

D)UNDEFINE COLUMN column_name","B""Which is the correct order of the mathematical operators?","A)- + / *

B)+ / - *

C)* / + -

D)* + - /","C""The WHERE clause restricts which of the following?","A)Rows

B)Columns

C)Groups

D)Tables","A""Is PL/SQL a programming language or a way to gather data?","Short Answer","It is a programming lanugauge. It uses SQL to gather data.""How do you read specific data from a table (such as name, department, etc)?","Short Answer","With a SELECT statement, such as:

SELECT ename, deptno FROM emp;""How do you list all items in a table?","Short Answer","With an asterisk in a SELECT statement, such as:

SELECT * FROM emp;

If your intention is to see which columns are in a table, use the DESCRIBE command of SQL*Plus.

DESCRIBE emp"

"Does Oracle store all data in upper case, lower case, or mixed?","Short Answer","Data is stored in both upper and lower case, such as an employee's name 'Jones'.

Column names and table names are stored in the Data Dictionary in upper case.""Which statement would produce the following results:

EMPNO ENAME SAL MGR--------- ---------- --------- --------- 7902 FORD 3000 7566 7369 SMITH 800 7902 7788 SCOTT 3000 7566 7876 ADAMS 1100 7788","A)SELECT empno, ename, sal, mgrFROM empWHERE mgr NOT IN (7902, 7566, 7788);

B)SELECT empno, ename, sal, mgrFROM empWHERE mgr IN (7902, 7566, 7788);

C)SELECT empno, ename, mgrFROM empWHERE empno NOT IN (7902, 7566, 7788);

D)SELECT empno, ename, sal, mgrFROM empWHERE empno IN (7902, 7566, 7788);","B""Why are Aliases better?","A)They make the column/table name more meaningful

B)They take up less memory

C)They just look better

D)They simplify things and make them more readable","D""If '&dept_name' is being inserted into the column department_name, what type of data is department_name?","A) numberB) blobC) varchar2D) date","C

Note: Single quotes (apostrophes) are also used when inserting dates, however 'department_name' would be a very bogus column name for a date column.""How many rows can you insert into a table.","A)As many as you want

B)As many as the physical space of the database will allow

C)

Depends on which version of Oracle you are running

D)Both B and C","Unknown, although I would guess D""Which of the following will always SELECT all columns and all rows from the emp table?","A)SELECT ALLFROM emp;

B)SELECT *FROM empWHERE sal IS NOT NULL;

C)SELECT *FROM emp;

D)SELECT *FROM empHAVING ALL ROWS;","C""For a given row which contains the value 'variable' in a column named 'type', what does the following function return?

SUBSTR(type, -3)","A) 'riable'

B) 'iable'

C) 'able'

D) 'ble'

E) none of the above","D""For a given row which contains the value 'Johnson' in a column named 'cust_name', what does the following function return?

SUBSTR(cust_name, 4, 3)","A) 'hnso'

B) 'nso'

C) 'nosn'

D) 'nos'","B""Which of the following is not a valid type of JOIN?","A) Non-EquijoinB) Self-joinC) Limited-joinD) Outer-joinE) All the above are valid","C""How do PRIMARY KEY and UNIQUE KEY Constraints differ?","A) They do not differ, but are two different ways to achieve the same result

B) The UNIQUE KEY Constraint allows Null values, PRIMARY KEY does not

C) The PRIMARY KEY Constraint allows Null values, UNIQUE does not

D) The PRIMARY KEY Constraint has an index, UNIQUE does not","B"

"How are PRIMARY KEY and UNIQUE KEY constraints alike?","Short Answer","They are alike in that both have indexes created for their columns automatically.

They differ as follows:

[ ] A primary key column can NOT contain NULL values, and all its values must be unique.

[ ] A unique key column CAN contain NULL values, however, if values are present (non-NULL), then the values must be unique.""List the types of joins which are available.","Short Answer","Non-EquijoinEqui-joinSelf-joinOuter-join""Evaluate the following expression:

8 * 2 / 4","Short Answer","8 * 2 / 4

16 / 4

4""Evaluate the following expression:

3 + 100 / 2","Short Answer","3 + 100 / 2

3 + 50

53""Evaluate the following expression:

8 - 2 + 4","Short Answer","8 - 2 + 4

6 + 4

10""Evaluate the following expression:

7 * (8 - 4) + (3 * 2)","Short Answer","7 * (8 - 4) + (3 * 2)

7 * (4) + (6)

7 * 4 + 6

28 + 6

34""Evaluate the following expression:

100 / 50 * 2","Short Answer","100 / 50 * 2

2 * 2

4""Evaluate the following expression:

100 / (50 * 2)","Short Answer","100 / (50 * 2)

100 / (100)

100 / 100

1""Evaluate the following expression:

2 + 2 - 4","Short Answer","2 + 2 - 4

4 - 4

0""A null in a character column is equivalent to blank, and in a numeric column is equivalent to zero.","True/False","False""A column alias precedes the column name in the select clause.","True/False","False""The keyword AS is optional when using column aliases.","True/False","True""The following syntax is correct for using a column alias:

SELECT emp 'Employee Name', sal Salary FROM emp;","True/False","False

The alias should be enclosed in DOUBLE quotes instead of SINGLE quotes (apostrophes).""Under which of the following circumstances should you use double quotes around a column alias?","A) It contains spacesB) It contains special charactersC) It is case sensitiveD) All of the aboveE) None of the above, you should use single quotes instead","D) All of the above""Within a SQL statement, a column alias CAN be used with both the SELECT and the ORDER BY clauses, but can NOT be used in the WHERE clause.","True/False","True""If a column alias is NOT enclosed in double quotes, it will be displayed in all capital letters.","True/False","True""What is the concatenation operator?","A) &&B) ++C) $$D) ||","D) ||""Which of the following SQL statements will result in the following display for a table with only three rows?

CUSTOMERS --------- Flo Jones Moe King Joe Brown 3 rows selected.","A) SELECT first_name, ' ', last_name 'CUSTOMERS'FROM cust;

B)SELECT first_name ' ' || ' ' last_name 'Customers'FROM cust;

C)SELECT first_name || last_name CUSTOMERSFROM cust;

D)SELECT first_name || ' ' || last_name CustomersFROM cust;","D)""Date and character literals are enclosed within single quotes, whereas aliases are enclosed within double quotes.","True/False","True""Date and character literals are enclosed within double quotes, whereas aliases are enclosed within single quotes.","True/False","False""Compose a SQL statement to concatenate the employee name, the literal ' works in ', and the location with a column heading in all caps of WORKSWHERE. A typical output would look like this: WORKSWHERE --------------------------------- KING works in NEW YORK ... 14 rows selected.","Short Answer","SELECT e.ename || ' works in ' || d.loc workswhereFROM emp e, dept dWHERE e.deptno = d.deptno;""Which of the following uses the correct syntax for eliminating duplicate rows?","A) SELECT ename, sal, deptnoFROM emp DISTINCT;

B)SELECT DISTINCT ename, sal, deptnoFROM emp;

C)SELECT UNIQUE ename, sal, deptnoFROM emp;

D)SELECT ename, sal, deptnoFROM emp NONDUPLICATE;","B)SELECT DISTINCT ename, sal, deptnoFROM emp;""Which of the following is based on ANSI standards?","A) SQLB) SQL*Plus","A) SQL""Which of the following has keywords which CAN be abbreviated?","A) SQLB) SQL*Plus","B) SQL*Plus""Which of the following has keywords which can NOT be abbreviated?","A) SQLB) SQL*Plus","A) SQL""Which of the following does NOT have a continuation character?","A) SQLB) SQL*Plus","A) SQL""Which of the following DOES have a continuation character?","A) SQLB) SQL*Plus","B) SQL*PlusIts continuation character is the dash (-).""Which of the following uses a termination character to execute the command immediately?","A) SQLB) SQL*Plus","A) SQL - uses the semi-colon""What three pieces of information do you provide to SQL*Plus when logging in remotely?","Short Answer","User NamePasswordHost String""What is the special character used to join the password and host string when using the CONNECT command?","Short Answer","@

as in:

SQL> conn scott/tiger@dba""What SQL*Plus command is used to display the structure of a table?","Short Answer","DESCRIBE

or

DESC""List some common SQL datatypes.","Short Answer","NUMBER(p,s)VARCHAR2(n)CHAR(n)DATE""What SQL*Plus command is used to empty out the SQL buffer?","Short Answer","CLEAR BUFFER

or

CL BUFF""What SQL*Plus command is used to display the contents of the SQL buffer?","Short Answer","LIST

or

L""What SQL*Plus command is used to execute the contents of the SQL buffer?","Short Answer","RUN

or

/""What SQL*Plus command is used to start recording of the screen display to an ASCII file?","Short Answer","SPOOL filename""What SQL*Plus command is used to stop spooling of the screen display?","Short Answer","SPOOL OFF""List the comparison operators (also known as relational operators).","Short Answer","=><>=<=<>BETWEEN . . . AND . . .LIKEINIS NULLIS NOT NULL

not equal to can also be written as:

!=""Which of the following will result in one or more rows being retrieved?","A) SELECT salFROM empWHERE sal BETWEEN 1500 AND 500;

B) SELECT salFROM empWHERE BETWEEN 1500 AND 500;

C) SELECT salFROM empWHERE sal BETWEEN 500 AND 1500;

D) SELECT salFROM empWHERE BETWEEN 500 AND 1500;","C) SELECT salFROM empWHERE sal BETWEEN 500 AND 1500;""Which of the following WHERE clauses uses the correct syntax?","A) WHERE IN 7902, 7566, 7788;

B)WHERE mgr IN 7902, 7566, 7788;

C)WHERE IN(7902, 7566, 7788);

D)WHERE mgr IN(7902, 7566, 7788);","D)WHERE mgr IN(7902, 7566, 7788);""The comparison operator BETWEEN . . . AND . . . excludes the end points of the range.","True/False","False""The comparison operator BETWEEN . . . AND . . . includes the end points of the range.","True/False","True""Given: A table has fourteen (14) rows with the following salaries (sal): 500, 600, 799, 799, 800, 800, 801, 1000, 1100, 1499, 1499, 1500, 1500, and 1501.

How many rows will be retrieved with the following SQL statement? SELECT sal FROM emp WHERE sal BETWEEN 800 AND 1500;","A) 5

B) 7

C) 9

D) 12","C) 9""The LIKE comparison operator uses which wildcard characters?","Short Answer","%(percent sign)for zero or many characters

_(underscore)denotes one character""For a column named 'tag' with a datatype of CHAR(6), what WHERE clause would you specify to look for all tags that had unknown characters in the first two positions, followed by a 'C' in the third position, followed by an unknown character in the fourth position, and '47' in the last two positions?","Short Answer","WHERE tag LIKE '__C_47';""Which of the following WHERE clauses results in listing all employees whose name begins with the letter 'H'?","A) WHERE ename LIKE 'H%';

B)WHERE ename LIKE 'H+';

C)WHERE ename LIKE 'H?';

D)WHERE ename LIKE 'H_';","A) WHERE ename LIKE 'H%';""List the three logical operators.","Short Answer","NOTANDOR""What is the correct order of evaluation for logical operators?","A) AND, NOT, ORB) AND, OR, NOTC) NOT, AND, OR D) NOT, OR, ANDE) OR, AND, NOTF) OR, NOT, AND","C) NOT, AND, OR""For the logical operator AND, fill in the following Truth Table (aka a Logic Table)?

AND TRUE FALSE NULL TRUE ---- ----- ---- FALSE ---- ----- ---- NULL ---- ----- ----","Short Answer","AND TRUE FALSE NULLTRUE TRUE FALSE NULLFALSE FALSE FALSE FALSENULL NULL FALSE NULL""For the logical operator OR, fill in the following Truth Table (aka a Logic Table)?

OR TRUE FALSE NULL TRUE ---- ----- ---- FALSE ---- ----- ---- NULL ---- ----- ----","Short Answer"," OR TRUE FALSE NULLTRUE TRUE TRUE TRUEFALSE TRUE FALSE NULL NULL TRUE NULL NULL""For the logical operator OR, fill in the following Truth Table (aka a Logic Table)?

NOT Result TRUE ------ FALSE ------ NULL ------","Short Answer","NOT ResultTRUE FALSEFALSE TRUENULL NULL""Which of the following statements ALWAYS results in NO rows being retrieved?","A) SELECT * FROM empWHERE sal < 1500AND sal > 500;

B) SELECT * FROM empWHERE sal > 1500OR sal < 500;

C)

SELECT * FROM empWHERE sal > 1500AND sal < 500;

D) SELECT * FROM empWHERE sal < 1500OR sal > 500;","C) SELECT * FROM empWHERE sal > 1500AND sal < 500;""Which of the following statements ALWAYS results in ALL rows being retrieved?","A) SELECT * FROM empWHERE sal < 1500AND sal > 500;

B) SELECT * FROM empWHERE sal > 1500OR sal < 500;

C) SELECT * FROM empWHERE sal > 1500AND sal < 500;

D) SELECT * FROM empWHERE sal < 1500OR sal > 500;","D) SELECT * FROM empWHERE sal < 1500OR sal > 500;""Which of the WHERE clauses below (multiple-choice) is equivalent to the following WHERE clause?

WHERE sal BETWEEN 800 AND 1500;","A) WHERE sal >= 800 AND sal <= 1500;

B) WHERE sal <= 800 AND sal >= 1500;

C) WHERE sal <= 800 OR sal >= 1500;

D) WHERE sal >= 800 OR sal <= 1500;","A) WHERE sal >= 800 AND sal <= 1500;""Which clause is used to sort rows?","Short Answer","ORDER BY""What is the default way in which rows are sorted when using the ORDER BY clause?","A) Ascending - ASCB) Descending - DESC","A) Ascending - ASC""If neither ASC nor DESC is used in conjunction with ORDER BY, which is the default?","Short Answer","ASC""Column aliases CAN be used in an ORDER BY clause.","True/False","True""Which of the following ORDER BY clauses results in both columns being sorted in descending order?","A) ORDER BY state, tag DESC;

B)ORDER BY state DESC, tag DESC;

C) ORDER BY DESC state, tag;

D)ORDER BY DESC state, DESC tag;","B)ORDER BY state DESC, tag DESC;""List nine (9) single row character functions.","Short Answer","LOWERUPPERINITCAPCONCATSUBSTRLENGTHINSTRLPADTRIM""What results from the following function? CONCAT ('Adam', 'Ant')","Short Answer","'AdamAnt'""Given: A product code such as 'ABC123MI99' contains the state where the product was manufactured. Compose a function to pick off the letters 'MI' from this string.","Short Answer","SUBSTR('ABC123MI99', 7, 2)""The column loc_code contains a two letter state abbreviation, a five digit zip code, and a one character plant code. Which of the following extracts the zip code from that column? An example of a value contained in loc_code is:

'MI49017B'","A) SUBSTR(loc_code, 7, 3)

B)SUBSTR(loc_code, 3, 7)

C)SUBSTR(loc_code, 3, 5)

D)SUBSTR(loc_code, 5, 3)","C)SUBSTR(loc_code, 3, 5)""What value does the following function return?

LENGTH('ABC123')","Short Answer","6""What values do the following functions return? (You will have four answers)

1 - ROUND(10.849, 1)

2 - ROUND(13.35, 1)

3 - ROUND(88.4649, 2)

4 - ROUND(88.4650, 2)","Short Answer","1 - 10.8

2 - 13.4

3 - 88.46

4 - 88.47"

"What values do the following functions return? (You will have four answers)

1 - TRUNC(10.849, 1)

2 - TRUNC(13.35, 1)

3 - TRUNC(88.4649, 2)

4 - TRUNC(88.4650, 2)","Short Answer","1 - 10.8

2 - 13.3

3 - 88.46

4 - 88.46""What value is returned by the following function?

MOD(17, 3)","Short Answer","2""What is the function which returns the current operating system date?","Short Answer","SYSDATE""List six date functions.","Short Answer","MONTHS_BETWEENADD_MONTHSNEXT_DAYLAST_DAYROUNDTRUNC""What values do the following functions return? (You will have six answers)

1 - MONTHS_BETWEEN('01-MAY-02', '01-MAY-03')2 - MONTHS_BETWEEN('01-MAY-03', '01-MAY-02')3 - ADD_MONTHS('31-JUL-99',3)4 - NEXT_DAY('07-OCT-02', 'WEDNESDAY')5 - LAST_DAY('15-OCT-02')6 - NEXT_DAY(LAST_DAY('13-OCT-02'), 'SATURDAY')","Short Answer","1 - minus 12 (-12)2 - positive 12 (12)3 - '31-OCT-99'4 - '09-OCT-02'5 - '31-OCT-02'6 - '02-NOV-02'""List some common elements used when converting a number to a character value.","Short Answer","$ dollar sign

9 digit nine

, comma

0 digit zero

. decimal point""List some common elements used when converting a date to a character value.","Short Answer","YYYYYEARMM

MONTHDYDAYDDDDDDfm""List the three conversion functions.","Short Answer","TO_CHARTO_DATETO_NUMBER""When converting a date column to a character value, the TO_CHAR function is used. What does the fill mode 'fm' at the beginning of the format do? (As below)

TO_CHAR(hiredate, 'fmDAY MONTH YYYY')","Short Answer","It suppresses leading zeroes and removes padded blanks.""How would you display 'No Commission' for those employees with either a zero commission or a null commission?","Short Answer","SELECTDECODE( NVL(comm, 0), 0, 'No Commission', comm) commissionFROM emp;""What is wrong with the following function?

NVL(comm, 'No Commission')","Short Answer","The column comm is a numeric column, therefore the replacement value must also be numeric.""Which function is used to replace null values with a replacement value?","Short Answer","NVL""What function and what format would you use to display the numerica value 1234567.99 as:

$1,234,567.99","Short Answer","TO_CHAR(1234567.99, '$9,999,999.99')""Compose a function to associate an employee's job with a required level of experience. Use the following table:

CLERK none SALESMAN some ANALYST moderate MANAGER high PRESIDENT high all others unknown","Short Answer","DECODE(job, 'CLERK', 'none', 'SALESMAN', 'some', 'ANALYST', 'moderate', 'MANAGER', 'high', 'PRESIDENT', 'high', 'unknown')""What term is used to describe the placing of one function inside another function?","Short Answer","nesting""If two tables are used to display data, but a WHERE clause is not used, what type of join results?","Short Answer","Cartesian Join

aka

Cartesian Product""If one table has 10 rows and the second table has 15 rows, how many rows result from a Cartesian Join?","A) 10B) 15C) 25

D) 150","D) 150""How many aliases are in the following SQL statement?

SELECT ename employee, sal salary, loc location FROM emp e, dept d;

Also, what type of join does the above illustrate?","Short Answer","Five aliases: 3 column aliases, and 2 table aliases

A Cartesian Join: Because there is no WHERE condition""List seven (7) group functions.","Short Answer","AVGCOUNTMAXMINSTDDEVSUMVARIANCE""Which of the following Equijoins is correctly written?","A) SELECT ename, locFROM emp, deptWHERE deptno = deptno;

B) SELECT ename, locFROM emp e, dept dWHERE deptno = deptno;

C) SELECT ename, locFROM e.emp, d.deptWHERE e.deptno = d.deptno;

D) SELECT ename, locFROM emp e, dept dWHERE e.deptno = d.deptno;","D) SELECT ename, locFROM emp e, dept dWHERE e.deptno = d.deptno;""Which of the following Non-equijoins is correctly written?","A) SELECT e.ename, e.sal, s.grade FROM emp, salgradeWHERE losal = sal;

B) SELECT ename, sal, grade FROM emp e, salgrade sWHERE e.sal >= s.losal AND e.sal <= s.hisal;

C) SELECT ename, sal, grade FROM emp, salgradeWHERE e.sal BETWEEN s.losal AND s.hisal;

D)

SELECT e.ename, e.sal, s.grade FROM emp e, salgrade sWHERE sal >= losal OR sal <= hisal;","B) SELECT ename, sal, grade FROM emp e, salgrade sWHERE e.sal >= s.losal AND e.sal <= s.hisal;""What is the outer join operator?","Short Answer","(+)

Which is an open parenthesis, followed by a plus sign, followed by a closing parenthesis.""The outer join operator ' (+) ' is placed on the side which is deficient in information.","True/False","True""The cars table has the columns make, model, and color. The makes table has a single column, make. Every make from the makes table matches a make in the cars table, however, some makes in the cars table do not have matching makes in the makes table. Cars: FORD, CHEVY, DODGE, GEO, FORD, CHEVY Makes: FORD, DODGECompose a query which shows the make and model for ALL cars, AND which displays the make from the makes table (if there is a matching make).","Short Answer","SELECT c.make, c.model, m.makeFROM cars c, makes mWHERE c.make = m.make (+);"

FREQUENTLY ASKED QUESTIONS:

1. Write a query to eliminate duplicate rows in a table?

DELETE FROM DEPT D WHERE D.ROWID! = (SELECT MAX (ROWID) FROM DEPT D1 WHERE D.DEPTNO = D1.DEPTNO AND D.DNAME = D1.DNAME AND D.LOC = D1.LOC)

2. Write a query to find max 5 salaries of employees?

Select sal from (select distinct (sal) from emp order by sal desc) Where rownum < 6

Top – n- Analysis.Select rownum as Rank, ename, Sal from (select ename, Sal from emp order by sal desc) where rownum <=3

3. Given a Procedure in a Package and a Procedure standalone what is the diff between the two and which is better to use?

Advantages of a package:

Modularity -Group logically related PL/SQL types, items, and subprograms. Easier Application Design bcoz you can code and compile a specification without its body. You

need not define the package body fully until you are ready to complete the application. Information Hiding -You can decide which constructs are public (visible and accessible) or private

(hidden and inaccessible). The package hides the definition of the private constructs (i.e they are not included in package specification) so that only the package is affected (not your application) if the definition changes. Also, by hiding implementation details from users, you protect the integrity of the package.Note: When coding the package body, the definition of the private function has to be above the definition of the public procedure.

Persistence - Packaged public variables and cursors persist for the duration of a session. Thus they can be shared by all subprograms that execute in the environment

Overloading -Packages allow you to overload procedures and functions, which means you can create multiple subprograms with the same name in the same package, each taking parameters of different number,order or datatype. Necessity of overloading is - Sometimes the processing in two subprograms is the same. In that case it is logical to give them the same name. PL/SQL determines which subprogram is being called by checking its formal parameters. Only local or packaged subprograms can be overloaded.

You cannot overload:•Two subprograms if their formal parameters differ only in name or parameter mode. (datatype and their total number is same).•Two subprograms if their formal parameters differ only in datatype and the different datatypes are in the same family (number and decimal belong to the same family)•Two subprograms if their formal parameters differ only in subtype and the different subtypes are based on types in the same family (VARCHAR and STRING are subtypes of VARCHAR2)•Two functions that differ only in return type, even if the types are in different families.Example of Overloading:

Package specification

CREATE OR REPLACE PACKAGE over_pack IS PROCEDURE add_dept (v_deptno IN dept.deptno%TYPE, v_name IN dept.dname%TYPE DEFAULT 'unknown', v_loc IN dept.loc%TYPE DEFAULT 'unknown');

PROCEDURE add_dept (v_name IN dept.dname%TYPE DEFAULT 'unknown', v_loc IN dept.loc%TYPE DEFAULT 'unknown'); END over_pack;

Package Body

CREATE OR REPLACE PACKAGE BODY over_pack IS PROCEDURE add_dept (v_deptno IN dept.deptno%TYPE, v_name IN dept.dname%TYPE DEFAULT 'unknown', v_loc IN dept.loc%TYPE DEFAULT 'unknown') IS BEGIN INSERT INTO dept VALUES (v_deptno,v_name,v_loc); END add_dept;

PROCEDURE add_dept (v_name IN dept.dname%TYPE DEFAULT 'unknown', v_loc IN dept.loc%TYPE DEFAULT 'unknown')

IS BEGIN INSERT INTO dept VALUES (dept_deptno.NEXTVAL,v_name,v_loc); END add_dept; END over_pack;

If you call ADD_DEPT with an explicitly provided department number, PL/SQL uses the first version of the procedure. If you call ADD_DEPT with no department number, PL/SQL uses the second version. EXECUTE OVER_PACK.ADD_DEPT (76,'MARKETING','ATLANTA')

EXECUTE OVER_PACK.ADD_DEPT ('SUPPORT','ORLANDO') Allow Oracle8 to read multiple objects into memory at once. When you call a packaged PL/SQL construct (subprogram) for the first time, the whole package is

loaded into memory. Thus, later calls to related constructs require no disk I/O.Note : Packages cannot be called, parameterized, or nested.

A procedure in a package is better to use bcoz: In case of stand alone procedure, whenever it is called it has to be loaded into memory thus disk

I/O takes place everytime while if the procedure is in a package then first time when we call the procedure from the package it gets loaded into memory and any later calls doesn’t require disk I/O.

Package procedure can be defined as public which can be called from other subprograms of the package and from outside the package.Similarly we can define public function and public variables.

Note: Package specification can exist without package body but package body cannot exist without package specification.To drop a package first drop package specification then package body.

DROP PACKAGE package_nameDROP PACKAGE BODY package_name

4. What is FORWARD DECLARATION in Packages?

PL/SQL allows for a special subprogram declaration called a forward declaration. It consists of the subprogram specification in the package body terminated by a semicolon. You can use forward declarations to do the following:• Define subprograms in logical or alphabetical order.• Define mutually recursive subprograms. (Both calling each other).• Group subprograms in a package

Example of forward Declaration:

CREATE OR REPLACE PACKAGE BODY forward_pack IS PROCEDURE calc_rating(. . .); -- forward declaration PROCEDURE award_bonus(. . .) IS -- subprograms defined BEGIN -- in alphabetical order calc_rating(. . .); . . . END; PROCEDURE calc_rating(. . .) IS BEGIN . . . END; END forward_pack;

5. PRAGMA RESTRICT_REFERENCES:•Checks that the restrictions of using functions in SQL statements are not violated•Allows packaged functions to be used in SQL statements•Verifies the purity of a function at compilation. The purity level asserts the extent to which the function permits database operations like insert,update or delete.

PRAGMA RESTRICT_REFERENCES is no longer required for Oracle8i.

PRAGMA RESTRICT_REFERENCES(function_name, WNDS --write no database state [,WNPS] --write no package state [,RNDS] --read no database state [,RNPS]);-- read no package state

CREATE OR REPLACE PACKAGE taxes_pack AS FUNCTION tax (v_value IN NUMBER) RETURN NUMBER; PRAGMA RESTRICT_REFERENCES (tax, WNDS, RNPS, WNPS); END taxes_pack;

ExampleEncapsulate the function, TAX, in a package, TAXES_PACK. The function will be called from SQL statements on remote databases. Therefore, you need to assert the RNPS, WNPS, and WNDS purity levels, because remote functions can neither read nor write the package variables, nor modify database tables when called from a SQL statement.

Note: we can declare the public (global) cursor in the package specification.

6. Name some Oracle Server supplied packages:–DBMS_PIPE–DBMS_DDL–DBMS_JOB–DBMS_OUTPUT •Write dynamic SQL using DBMS_SQL and EXECUTE IMMEDIATE

DBMS_PIPE PackageThe DBMS_PIPE package performs the following functions:•It allows two or more sessions connected to the same instance (vis) to communicate through a pipe just like pipes used in UNIX•Each pipe works asynchronously•Depending on your security requirements, you can use either a public pipe or a private pipe•Once buffered information is read by one user, it is emptied from the buffer, and is not available for other readers of the same pipe•To send a message, first make one or more calls to PACK_MESSAGE to build your message. Then call SEND_MESSAGE to send the message on the named pipe•To receive a message from a pipe, first call RECEIVE_MESSAGE, and then call UNPACK_MESSAGE to access the individual items in the messageOracle pipes buffer information in the SGA, which means that information is lost if you shut down your instance.

Example:

CREATE OR REPLACE PROCEDURE send_message (v_message IN VARCHAR2) IS s INTEGER;BEGIN DBMS_PIPE.PACK_MESSAGE(v_message); s := DBMS_PIPE.SEND_MESSAGE('DEMO_PIPE'); IF s <> 0 THEN RAISE_APPLICATION_ERROR (-20200, 'Error '||TO_CHAR(s)||' sending on pipe.'); END IF;END send_message;

CREATE OR REPLACE PROCEDURE receive_message IS s INTEGER; v_message VARCHAR2(50); BEGIN s := DBMS_PIPE.RECEIVE_MESSAGE('DEMO_PIPE'); IF s <> 0 THEN RAISE_APPLICATION_ERROR (-20201, 'Error '||TO_CHAR(s)||' reading pipe.'); END IF; DBMS_PIPE.UNPACK_MESSAGE(v_message); DBMS_OUTPUT.PUT_LINE(v_message); END receive_message;

Dynamic SQL

Advantages: Dynamic SQL to create a procedure that operates on a table whose name is not known until runtime, or to

write and execute a data definition language (DDL) statement in PL/SQL.In Oracle8, and earlier, you have to use DBMS_SQL to write dynamic SQL.In Oracle 8i, you can use DBMS_SQL, EXECUTE IMMEDIATE. If the statement is a multirow SELECT, you can use DBMS_SQL or OPEN-FOR, FETCH, and CLOSE statements.

Disadvantage of dbms_sql: Using this package to execute DDL statements can result in a deadlock. The most likely reason for this is if,

for example, the package is being used to drop a procedure, which is still in use by you.

Steps to Process SQL Statements:All SQL statements have to go through various stages. Not all the stages are mandatory, and some stages may be missed.

ParseEvery SQL statement must be parsed. Parsing the statement includes checking the statement's syntax and validating the statement, ensuring that all references to objects are correct, and ensuring that the relevant privileges to those objects exist.

BindAfter parsing, Oracle knows the meaning of the Oracle statement but still may not have enough information to execute the statement. Oracle may need values for any bind variable in the statement. The process of obtaining these values is called binding variables.

ExecuteAt this point, Oracle has all necessary information and resources, so the statement is executed.

FetchIn the fetch stage, rows are selected and ordered (if requested by the query), and each successive fetch retrieves another row of the result, until the last row has been fetched.Some of the procedures and functions of the DBMS_SQL package:•OPEN_CURSOR•PARSE

•BIND_VARIABLE•EXECUTE•FETCH_ROWS•CLOSE_CURSOR

SYNTAX of DBMS_SQL:

CREATE OR REPLACE PROCEDURE delete_all_rows (tab_name IN VARCHAR2, rows_del OUT NUMBER) IS cursor_name INTEGER; BEGIN cursor_name := DBMS_SQL.OPEN_CURSOR; DBMS_SQL.PARSE ( cursor_name,'delete FROM '||tab_name, DBMS_SQL.NATIVE ); rows_del := DBMS_SQL.EXECUTE (cursor_name);

DBMS_SQL.CLOSE_CURSOR(cursor_name);

SQL> VARIABLE deleted NUMBERSQL> EXECUTE delete_all_rows('emp',:deleted)PL/SQL procedure successfully completed.SQL> PRINT deleted DELETED--------- 14

Dynamic SQL with Oracle8i using EXECUTE IMMEDIATE:

CREATE PROCEDURE del_rows (v_table_name IN VARCHAR2, rows_deld OUT NUMBER)ISBEGIN EXECUTE IMMEDIATE 'delete from '||v_table_name; rows_deld := SQL%ROWCOUNT;END;SQL> VARIABLE deleted NUMBERSQL> EXECUTE del_rows('emp',:deleted)PL/SQL procedure successfully completed.SQL> PRINT deleted DELETED--------- 14

DBMS_DDL Package

Uses:

•You can recompile your modified procedures, functions, and packages using DBMS_DDL.ALTER_COMPILE.

ALTER_COMPILE (object_type, owner, object_name)DBMS_DDL.ALTER_COMPILE('PROCEDURE','A_USER','QUERY_EMP')•You can analyze a single object, using DBMS_DDL.ANALYZE_OBJECT. (There is a way of analyzing more than one object at a time, using DBMS_UTILITY.)

ANALYZE_OBJECT (object_type, owner, name, method)DBMS_DDL.ANALYZE_OBJECT('TABLE','A_USER','EMP','COMPUTE')

•This package gives developers access to ALTER and ANALYZE SQL statements through PL/SQL environments.

DBMS_JOB Package

Allows tasks to be scheduled and altered once in the queue. Some procedures in the package:•SUBMIT (jobno, what, next_date).–JOB is an out parameter, which will contain the number allocated for the job.–WHAT is the statement you want to execute.–NEXT_DATE is the date of execution. The default is SYSDATE.•RUN (jobno): Force a submitted job to execute now

Note : USER_JOBS – Data dictionary view is used to see the jobs in the queue.

Example:

SQL> VARIABLE jobno NUMBERSQL> EXECUTE DBMS_JOB.SUBMIT (:jobno, -> 'OVER_PACK.ADD_DEPT(''EDUCATION'',''ZURICH'');', - > SYSDATE)SQL> COMMIT;SQL> PRINT jobno

•You can force a job in the queue to run now, if you supply the job numberDBMS_JOB.RUN (jobno)

DBMS_OUTPUT PackageAllows you to output messages from PL/SQL blocksSome of the procedures of the package:•PUT•NEW_LINE•PUT_LINE•GET_LINE•GET_LINES•ENABLE/DISABLESome other Oracle supplied packages:

•DBMS_ALERT•DBMS_APPLICATION_INFO•DBMS_DESCRIBE•DBMS_LOCK•DBMS_SESSION•DBMS_SHARED_POOL•DBMS_TRANSACTION•DBMS_UTILITY•UTL_FILE

7. What is the sequence of firing of database triggers?

Total 12 database triggers – insert/update/delete – before/after – row/statement.

Sequence of firing:

When single row is manipulated in trigger:Before statement

Before rowAfter rowAfter statement

When multiple row is manipulated in trigger:Before statementBefore rowAfter rowBefore rowAfter row------After statement

Example of a statement trigger:

Create one trigger to restrict all data manipulation events on the EMP table to certain business hours, Monday through Friday.

CREATE OR REPLACE TRIGGER secure_empBEFORE INSERT OR UPDATE OR DELETE ON empBEGIN IF (TO_CHAR (sysdate,'DY') IN ('SAT','SUN')) OR (TO_CHAR (sysdate, 'HH24') NOT BETWEEN '08' AND '18') THEN IF DELETING -keywords given by oracle in case of such triggers THEN RAISE_APPLICATION_ERROR (-20502, 'You may only delete from EMP during normal hours.'); ELSIF INSERTING THEN RAISE_APPLICATION_ERROR (-20500, 'You may only insert into EMP during normal hours.'); ELSIF UPDATING ('SAL') THEN RAISE_APPLICATION_ERROR (-20503, 'You may only update SAL during normal hours.'); ELSE RAISE_APPLICATION_ERROR (-20504, 'You may only update EMP during normal hours.'); END IF; END IF;END;Example of a row trigger:

SQL> CREATE OR REPLACE TRIGGER DERIVE_COMMISSION_PCT 2 BEFORE INSERT OR UPDATE OF sal ON emp 3 FOR EACH ROW 4 BEGIN 5 IF NOT (:NEW.JOB IN ('MANAGER' , 'PRESIDENT')) 6 AND :NEW.SAL > 5000 7 THEN 8 RAISE_APPLICATION_ERROR 9 (-20202, 'EMPLOYEE CANNOT EARN THIS AMOUNT'); 10 END IF; 11 END;

8. What are old and new qualifiers in triggers?

--After deleting or inserting or updating on emp –insert the data in audit_emp_table to track all the changes done on emp table.

SQL>CREATE OR REPLACE TRIGGER audit_emp_values 2 AFTER DELETE OR INSERT OR UPDATE ON emp 3 FOR EACH ROW

4 BEGIN 5 INSERT INTO audit_emp_table (user_name, 6 timestamp, id, old_last_name, new_last_name, 7 old_title, new_title, old_salary, new_salary) 8 VALUES (USER, SYSDATE, :OLD.empno, :OLD.ename, 9 :NEW.ename, :OLD.job, :NEW.job,:OLD.sal, :NEW.sal ); 11 END; 12 /-- : old is used for the values before change and new for after change.

9. Difference between row and statement trigger?

Statement Triggers and Row TriggersYou can specify the number of times the trigger action is to be executed: once for every row affected by the triggering statement (such as a multiple row UPDATE) , or once for the triggering statement no matter how many rows it affects.Statement TriggerA statement trigger is fired once on behalf of the triggering event, even if no rows are affected at all.Statement triggers are useful if the trigger action does not depend on data of rows that are affected or data provided by the triggering event itself. For example, a trigger that performs a complex security check on the current user.Row TriggerA row trigger fires each time the table is affected by the triggering event. If the triggering event affects no rows, a row trigger is not executed at all.Row triggers are useful if the trigger action depends on data of rows that are affected or data provided by the triggering event itself.

10. How can you restrict a row trigger?

To restrict the trigger action to those rows that satisfy a certain condition, provide a WHEN clause.Example:Create a trigger on the EMP table to calculate an employee’s commission when a row is added to the EMP table or an employee’s salary is modified.

SQL>CREATE OR REPLACE TRIGGER derive_commission_pct 2 BEFORE INSERT OR UPDATE OF sal ON emp 3 FOR EACH ROW 4 WHEN (NEW.job = 'SALESMAN') 5 BEGIN 6 IF INSERTING 7 THEN :NEW.comm := 0; 8 ELSIF :OLD.comm IS NULL 9 THEN :NEW.comm := 0; 10 ELSE :NEW.comm := :OLD.comm * (:NEW.sal/:OLD.sal); 11 END IF; 12 END; 13 /The NEW qualifier does not need to be prefixed with a colon in the WHEN clause.Note: If we use after insert or update then we will get a compilation error.ORA-04084: cannot change NEW values for this trigger type

Bcoz new can only be used with before triggers.11. What are instead of triggers?

Instead of trigger is a trigger created on a complex view (with more than 1 table) to modify them, as complex views are inherently non-modifiable.

These triggers are called INSTEAD OF triggers, because, unlike other triggers, Oracle server fires the trigger instead of executing the triggering statement (insert/update/delete). . Ex- create trigger tst instead of insert on emp_view …do something

Why Use INSTEAD OF Triggers?If a view consists of more than one table, an insert to the view may entail an insert into one table and an update to another. So, you write an INSTEAD OF trigger that fires, when you write an insert against the view. Instead of the original insert, the trigger body executes, which results in an insert into one table and an update to another table.ex- if we insert a row in emp table with emp salary. And there is another table total which sums total sal for each department . In that case whenever an insert will be on emp table then table – total will also get updated.

12. Difference between trigger and stored procedure?

Triggers ProcedureUse CREATE TRIGGER Use CREATE PROCEDUREData dictionary contains source and p-code Data dictionary contains source and p-codeImplicitly invoked Explicitly invokedCOMMIT, SAVEPOINT, ROLLBACK not allowed COMMIT, SAVEPOINT, ROLLBACK allowed

13. Restrictions on instead of triggers:1. Available only on row level not on statement level.2. Can be applied only to views not on tables.3. Cannot use ‘WHEN’ clause to restrict instead of trigger.

Note: ALTER TRIGGER trigger_name DISABLE | ENABLE ALTER TRIGGER trigger_name DISABLE | ENABLE ALL TRIGGERS ALTER TRIGGER trigger_name COMPILE --to recompile the trigger

14. What are logon and log off trigger?

You can create this trigger to monitor how often you log on and off, or you may want to write a report on how long you are logged on for.Example:SQL> CREATE OR REPLACE TRIGGER LOGON_TRIG 2 AFTER logon ON SCHEMA 3 BEGIN 4 INSERT INTO log_trig_table 5 (user_id, log_date, action) 6 VALUES (user, sysdate, 'Logging on'); 7 END;SQL> CREATE OR REPLACE TRIGGER LOGOFF_TRIG 2 BEFORE logoff ON SCHEMA 3 BEGIN 4 INSERT INTO log_trig_table 5 (user_id, log_date, action) 6 VALUES (user, sysdate, 'Logging off'); 7 END;

15. How do we call a procedure in a trigger?

CALL statement is used to call a stored procedure, rather than coding the PL/SQL body in the trigger itself.

CREATE TRIGGER TEST3 2 BEFORE INSERT ON EMP 3 CALL proc1 – where proc1 is the name of stored procedure.

16. What is a mutating table?Example:

This trigger, CHECK_SALARY, guarantees that whenever a new employee is added to the EMP table or an existing employee’s salary or job title is changed, the employee’s salary falls within the established salary range for the employee’s job.

SQL> CREATE OR REPLACE TRIGGER check_salary 2 BEFORE INSERT OR UPDATE OF sal, job ON emp 3 FOR EACH ROW 4 WHEN (new.job <> 'PRESIDENT') 5 DECLARE 6 v_minsalary emp.sal%TYPE; 7 v_maxsalary emp.sal%TYPE; 8 BEGIN 9 SELECT MIN(sal), MAX(sal) 10 INTO v_minsalary, v_maxsalary 11 FROM emp 12 WHERE job = :new.job; 13 IF :new.sal < v_minsalary OR 14 :new.sal > v_maxsalary THEN 15 RAISE_APPLICATION_ERROR(-20505,'Out of range'); 16 END IF; 17 END; 18 /SQL> UPDATE emp 2 SET sal = 1500 3 WHERE ename = 'SMITH';*ERROR at line 2:ORA-04091: table EMP is mutating, trigger/function may not see itORA-06512: at "CHECK_SALARY", line 5ORA-04088: error during execution of trigger 'CHECK_SALARY'

The EMP table is mutating, or in a state of change therefore the trigger cannot read from it.

17. Some commands to do Auditing?

SQL> AUDIT INSERT, UPDATE, DELETE 2 ON emp 3 BY ACCESS 4 WHENEVER SUCCESSFUL;AUDIT ROLE;AUDIT ROLE WHENEVER SUCCESSFUL;AUDIT ROLE WHENEVER NOT SUCCESSFUL;AUDIT SELECT TABLE, UPDATE TABLE;AUDIT SELECT TABLE, UPDATE TABLE BY scott, blake;AUDIT DELETE ANY TABLE;

18. When is ‘RAISE_APPLICATION_ERROR’ used?

It is a procedure that lets you issue user-defined error messages from stored subprograms.raise_application_error (error_number,message[, {TRUE | FALSE}]);

Can be called from executable as well as exception section of a subprogram.

19. What is an exception and what are its types ? Name some pre-defined exceptions.

Exception is an error in PL/SQL. Types of exceptions are:1. Pre-defined exceptions in Oracle Server - Implicitly raised

2. Non-PreDefined exceptions in Oracle Server - Implicitly raised3. User Defined -- Explicitly raised

•Sample predefined exceptions: –NO_DATA_FOUND ex- when no_data_found then rollback;–TOO_MANY_ROWS–INVALID_CURSOR–ZERO_DIVIDE–DUP_VAL_ON_INDEX

Non-PreDefined exceptions:- first name the exception ----Declare- Code the pragma EXCEPTION_INIT ----Associate- Handle the raised exception or explicitly raise it by RAISE command. --Reference

Ex- Trap for Oracle7 Server error number -2292 an integrity constraint violation.

/* PRAGMA EXCEPTION_INIT (initialize) used to associate the exception with an error number */

DECLARE e_products_remaining EXCEPTION; PRAGMA EXCEPTION_INIT (e_products_remaining, -2292);. . .BEGIN. . .EXCEPTION WHEN e_products_remaining THEN TEXT_IO.PUT_LINE ('Referential integrity constraint violated.');. . .END;

User Defined exceptions:- first name the exception ----Declare- Explicitly raise it by RAISE command

[DECLARE] e_amount_remaining EXCEPTION;. . .BEGIN. . .if….then RAISE e_amount_remaining;. . .EXCEPTION WHEN e_amount_remaining THEN :g_message := 'There is still an amount in stock.';. . .END;

20. Functions for trapping errors?

•WHEN OTHERS exception handler –Traps all exceptions not yet handled.–Is the last handler.•SQLCODE–Returns the numeric value for the error code.•SQLERRM

–Returns the message associated with the error number.

DECLARE v_error_code NUMBER; v_error_message VARCHAR2(255);BEGIN...EXCEPTION... WHEN OTHERS THEN ROLLBACK; v_error_code := SQLCODE ; v_error_message := SQLERRM ; INSERT INTO errors VALUES(v_error_code, v_error_message);END;

21. In which scenario database triggers will be used.Name the database triggers. Diff between database triggers and form transactional triggers ?

22. Types of loops :

While loopWHILE v_counter <= 10 LOOP INSERT INTO s_item (ord_id, item_id) VALUES (v_ord_id, v_counter); v_counter := v_counter + 1; END LOOP;

For loopFOR index in [REVERSE]

lower_bound..upper_bound LOOP Statement1; Statement2; . . .END LOOP;

Basic LoopLOOP INSERT INTO s_item (ord_id, item_id) VALUES (v_ord_id, v_counter); v_counter := v_counter + 1; EXIT WHEN v_counter > 10; END LOOP;23. Name the sql cursor attributes?

SQL%ROWCOUNT Number of rows affected by the most recent SQL statement (an integervalue).

SQL%FOUND Boolean attribute that evaluates to TRUE if the most recent SQL statement affects one or more rows.

SQL%NOTFOUND Boolean attribute that evaluates to TRUE if the most recent SQLstatement does not affect any rows.

SQL%ISOPEN Always evaluates to FALSE because PL/SQL closes implicit cursorsimmediately after they are executed.

24. Can we create a cursor without declaring it?

Yes – by using cursor for loop using subqueries.

BEGIN FOR emp_record IN (SELECT empno, ename

FROM EMP) LOOP -- Implicit open and implicit fetch occur IF emp_record.empno = 7839 THEN ... END LOOP; -- implicit close occursEND;

25. Can we pass Parameters in cursor? If yes then how do we populate them?What is cursor for loop? Why is WHERE CURRENT OF clause used in cursors?

Yes we can pass as shown below:CURSOR emp_cursor

(v_dept NUMBER, v_job VARCHAR2) IS SELECT last_name, salary, start_date FROM s_emp WHERE dept_id = v_dept AND title = v_job;BeginOpen emp_cursor (10,’FACULTY’) ---parameters are passed in open cursor statementsFetch cursor into v1,v2Close emp_cursor;

Cursor for loop (shortcut for explicit cursors, no need to open, fetch and close)CURSOR emp_cursor(v_dept NUMBER, v_job VARCHAR2) IS SELECT last_name, salary, start_date FROM s_emp WHERE dept_id = v_dept AND title = v_job;BeginFor emp_data in emp_cursor loop –no need to declare variable emp_data.--------Emp_data.last_name: = ‘Sharma’;

End loop;

WHERE CURRENT OF Clause•Update or delete the current row using cursors.•Lock the rows first by including the FOR UPDATE clause in the cursor query.

Syntax:

CURSOR emp_cursor IS SELECT...

FOR UPDATE;BEGIN ... FOR emp_record IN emp_cursor LOOP UPDATE... WHERE CURRENT OF emp_cursor; ... END LOOP;

COMMIT;END;

Cursor with subqueries

Retrieve department number, dname and count of staff from dept and EMP table where Count >=5

DECLARE CURSOR my_cursor IS SELECT t1.deptno, dname,STAFF FROM dept t1, (SELECT deptno, count (*) STAFF FROM EMP

GROUP BY deptno) t2 –retrieves count of staff in each dept.This query is used in place of a table

WHERE t1.deptno = t2.deptno AND STAFF >= 5;

26. Types of variables in PL/SQL?

•PL/SQL variables–Scalar–Composite–Reference–LOB (large objects)

Internal LOBs:- CLOB (Character LOB)- BLOB (Binary LOB) - photos- NLOB (national language character large object) External LOBs:- BFILE (binary file) – files in database or O/s system

•Non-PL/SQL variables–Bind and host variables

Note: DBMS_LOB package is used to manipulate the LOB.

DBMS_LOB.READCall the READ procedure to read and return piecewise a specified AMOUNT of data from a given LOB, starting from OFFSET.

DBMS_LOB.WRITECall the WRITE procedure to write piecewise a specified AMOUNT of data into a given LOB, from the user-specified BUFFER, starting from an absolute OFFSET from the beginning of the LOB value. DBMS_LOB.SUBSTR (substr from clob)DBMS_LOB.INSTR (search information from clob)

27. What is the use of EMPTY_CLOB()/EMPTY_BLOB()?

The use of function EMPTY_CLOB() or EMPTY_BLOB() means that the LOB is initialized, but not populated with data.Later can be populated by update statement. If you use NULL as the value for the LOB column, the LOB is not initialized; therefore, it can not be populated using an update statement.

Initialize a LOB column using functions EMPTY_CLOB() / EMPTY_BLOB()INSERT INTO employee (emp_id, emp_name, resume, picture)VALUES(7898, 'Marilyn Monroe', EMPTY_CLOB(),NULL);

28. What are temporary LOBs?

Temporary LOBs are new to Oracle8i. Temporary LOBs can be BLOBs, CLOBs, or NCLOBs.

Temporary LOB features:•Data is stored in your temporary tablespace.•They are not stored permanently in the database.•All temporary LOBs are deleted at the end of the session in which they were created.•They are not associated with a table.•Create a temporary LOB using DBMS_LOB.CREATETEMPORARY.Temporary LOBs are useful when you want to perform some transformational operation on a LOB, for example changing a LOB from one format to another, and then return it to the permanent LOB. A temporary LOB will be empty when created and it does not support the EMPTY_B/C/NCLOB functions.Use the DBMS_LOB package to use and manipulate temporary LOBs.

29. What is the diffrence between Long Raw and LOB datatype?

LONG, LONG RAW LOBSingle column per table Multiple columns per tableUp to 2 GB Up to 4 GBSELECT returns data SELECT returns locatorData stored in-line Data stored in-line or out-of-lineSequential access to data Random access to data

30. What are composite datatypes like we have scalar (number,char,varchar etc.). Name them and write the Syntax for them?

Composite Data types:– PL/SQL TABLES– PL/SQL RECORDS

- Nested TABLE - VARRAY

Advantage:–Contain internal components.–Are reusable.

•PL/SQL TABLES–Are composed of two components:•Primary key of datatype BINARY_INTEGER•Column of scalar datatype

Adv –Increase dynamically because they are unconstrained.

Syntax:

DECLARE TYPE ename_table_type IS TABLE OF emp.ename%TYPE INDEX BY BINARY_INTEGER; TYPE hiredate_table_type IS TABLE OF DATE INDEX BY BINARY_INTEGER; ename_table ename_table_type; hiredate_table hiredate_table_type;

BEGIN ename_table(1) := 'CAMERON'; hiredate_table(8) := SYSDATE + 7; IF ename_table.EXISTS(1) THEN

INSERT INTO ... ...END;

The primary key (i.e index value) can be negative. Indexing need not start with 1.Note: The table.EXISTS(i) statement returns TRUE if at least one row with index i is returned. Use the EXISTS statement to prevent an error which is raised in reference to a non-existing table element.Note: If TYPE ename_table_type IS TABLE OF emp%ROWTYPEThen composite datatype is called – PL/SQL TABLE OF RECORDS.

PL/SQL RECORD•Treat a collection of fields as a logical unit.•Are convenient for fetching a row of data from a table for processing.emp_recordpe IS RECORDemp_recordpe IS RECORD

(last(last emp_record_type;emp_record_type;Syntax:

TYPE emp_record_type IS RECORD (last_name VARCHAR2(25), first_name VARCHAR2(25), gender CHAR(1)); employee_record emp_record_type;

TYPE emp_record_type TYTYPE emp_record_type TYTYPE emp_record_type IS RECORDTYPE emp_record_type IS RECORD

emp_record.last_name := 'Maduro';emp_record.first_name := 'Elena';emp_record.gender := 'F';

How pl/sql record is used in a procedure: PROCEDURE all_dept (v_dept_id IN NUMBER)IS dept_record s_dept%ROWTYPE; BEGIN SELECT * INTO dept_record --PL/SQL RECORD FROM s_dept WHERE id = v_dept_id; ...END all_dept;

gendergender CHAR(1));CHAR(1));31. Uses of decode function with example?

32. What is accept, variable and print command in sql* plus?

•ACCEPT–Accepts input from the user and stores the input into a variable.

Sql> ACCEPT p_sal PROMPT 'Enter the salary: ' /*salary entered by user is stored in p_sal */

•VARIABLE–Declares a bind or host variable.Sql> Variable abc Number (10)Sql> Print abcINE DNAME = SALES

SQL>SELT NAME FROM S_DEPT WHERE LO

•DEFINESql> Define dname = ‘sales’ Sql> Select dname from dept where dname = ‘&dname’ --sales value is assigned to dname initially so query gives result for sales dept.UNDEFINE command is used to clear the variable.

NA SQL>DEFINE DNAME = SALESSQL>•PRINT–Displays the current value of bind variables.

Example : Input the monthly salary. Output the calculated annual salary.

ACCEPT p_sal PROMPT 'Enter the salary: ' /*salary entered by user is stored in p_sal */VARIABLE g_year_sal NUMBER

DECLARE v_sal NUMBER := &p_sal;

BEGIN :g_year_sal := v_sal * 12;

END;/PRINT g_year_sal

•EXECUTE–Executes a particular sql statement.

33. Can we drop a column in oracle 8i ? If yes then what is the commandTo do that ?

ALTER TABLE A DROP COLUMN ENO;

34. A table contains a column – gender with values ‘Male’ and ‘Female’.Write a query to find the count of all male and female emplyees in the company . Output should give 2 columns showing the count of male and female employees ?

SELECT gender, COUNT (*) FROM emp GROUP BY gender;

35. In a select statement if count function is used and a group by clause is not used then will it give an error? If yes then which error?

ORA-00937: not a single-group group function

36. What is the difference between ‘IN ‘ and ‘EXISTS’ operator in sql ?

37. What is the sequence of functions – group by,having,orderby in a select statements ?

Select…..Group by…Having…Orderby..

38. Name some date functions?

•MONTHS_BETWEEN('01-SEP-95','11-JAN-94') 1.9774194•ADD_MONTHS('11-JAN-94',6) '11-JUL-94'•NEXT_DAY('01-SEP-95','FRIDAY') '08-SEP-95'•LAST_DAY('01-SEP-95') '30-SEP-95'

39. Name some conversion functions?

•TO_CHAR converts a number or date string to a character string.•TO_NUMBER converts a character string containing digits to a number.•TO_DATE converts a character string of a date to a date value.

40. Use of an ‘Escape’ identifier?

ESCAPE identifier is used to search for "%" or "_".

41. What is RR date format

42. How can we see the code of a subprogram ?Using view – USER_SOURCEselect text from user_source where name = ‘ABC’;

Other views are –DICTIONARY, DICT_COLUMNS, USER_OBJECTS, USER_CONSTRAINTS, USER_CONS_COLUMNS, USER_INDEXES , USER_IND_COLUMNS ,USER_ERRORS (to see error details of a subprogram),USER_TRIGGERS,USER_DEPENDENCIES (to check subprograms reference which database objects like tables,views etc.)

Column Description for USER_SOURCENAME Name of the objectTYPE Type of object (Procedure, function)LINE Line number of the source codeTEXT Text of the source code line

43. Can 2 subprograms say one function and the other procedure can have same name.

No. 2 subprograms of different type cannot have same name.U will get error saying that – ORA-00955: name is already used by an existing object.

44. What is an implicit and explicit rollback.

When an sql statement fails then only that statement is rolled back bcoz oracle creates an implicit savepoint for each statement.Explicit rollback is given by user.

45. How can we drop a table and its dependent integrity constraints?

DROP TABLE table [CASCADE CONSTRAINTS];

46. Command to execute a procedure and a function?

Execute abc (arguments) – where abc is procedure name.Variable v_1 number

EXECUTE v_1 := function_name [(argument_list)]

47. Which table stores subprogram errors?User_errors

48. How to change Oracle password?

Alter user <username> identified by <pwd>WITH GRANT OPTION w3ith Grant command gives a user authority to pass along the privilegesGRANT select ON s_emp TO scott

WITH GRANT OPTION;

Grant privelege to all users. GRANT select ON s_ord_id TO PUBLIC;

49. Types of privileges?

•System privileges (ex- create session, create table etc.)–Gain access to the database•Object privileges (grant select, update on a table)–Manipulate the content of the database objects

50. How to see which user has logged in?

Sql>show user

51. What is the difference between PK and Unique key? What is a candidate and composite primary key and foreign key?

PK can never be null and is always unique while unique key column can be null.Candidate key is a key that can be used as a PK.Composite primary key is formed with more than one PK column.A foreign key (FK) is a column or combination of columns in one table that refers to a PK or unique key (UK) in the same table or in another table.Constraint that can only be defined at column level is: NOT NULL constraint.Note: When u create a table by using a subquery then only the NOT NULL

Constraint is copied. Add a NOT NULL constraint by using the MODIFY clause

52. What happens when u don’t give name to a constraint?

Server will generate a name by using the SYS_Cn format.

53. What is the use of ON DELETE CASCADE clause in a table?

–Allows deletion in the parent table and deletion of the dependent rows in the child table.54. Suppose we create a sequence ,insert data in the table using that sequence and then drop that sequence ?

what will happen to the present state of data.

55. How to add comments on a table or column?

You can add comments to a table or column by using the COMMENT command.

SQL> COMMENT ON TABLE s_emp IS 'Employee Information';Comment created

56. What are WITH CHECK OPTION CONSTRAINT and WITH READ ONLY in a view?

SQL> CREATE OR REPLACE VIEW empvu41 2 AS SELECT *

3 FROM s_emp 4 WHERE dept_id = 41 5 WITH CHECK OPTION CONSTRAINT empvu41_ck;View created.If you attempt to change the department number for any rows in the view, the statement will fail because it violates the CHECK OPTION constraint.Ensure that no DML operations occur by adding the WITH READ ONLY option to your view definition in case of simple views.Note:–A view can be dropped without removing the underlying data.(That means when we add or update or delete rows from simple view thenthe underlying table also gets reflected)

57. What is normalization and what are the 3 normal forms?Benefits of Normalization:•Minimizes data redundancy•Reduces integrity problems. (Entity, column, referential integrity are maintained.)•Identifies missing entities, relationships, and tables

Rule DescriptionFirst normal form All attributes must be single-valued.(Intersection of a row and column must be a

single value).Second normal form An attribute must depend upon its entity's entire UID (Unique identifier).

( Each table should have a PK column and Other columns of a table must depend on PK column of the table)

Third normal form No non-UID attribute can be dependent upon another non-UID attribute.

58. Types of data integrity constraints?

•Entity–No part of a primary key can be NULL and the value must be unique. A NULL is an absence of a value.•Referential–Foreign key values must match a primary key or be NULL.•Column–Values in the column must match the defined datatype.•User-defined–Values must comply with the business rules.

59. Write a query to select all even and odd number of rows from the table? (Hint :usemod function)

60. How the null values are displayed in case of order by clause by asc or desc.For asc – 1---1000 null values are displayed at the end.For desc – 1000---1 null values are displayed first.

61. Advantage & Disadvantage of using Truncate command over Delete command?

Truncate table <table_name> –Removes all rows from a table.–Releases the storage space used by that table.Disadvantage is that it is a DDL command so cant be rolled back.

62. Difference between in,out and inout parameters?

IN OUT IN OUT1. Default must be specified. Must be specified.

Value isPassed into Returned to calling Passed into subprogram; subprogram. Environment. Returned to calling env.

Formal parameter acts asA constant. An uninitialized an initialized variable. Variable Actual parameterCan be a literal, Must be a variable Must be a variable.expression, constant, orinitialized variable. Ex- of IN OUT parameter.

SQL> CREATE OR REPLACE PROCEDURE format_phone 2 (v_phone_no IN OUT VARCHAR2) 3 IS 4 BEGIN 5 v_phone_no := '(' || SUBSTR(v_phone_no,1,3) || 6 ')' || SUBSTR(v_phone_no,4,3) || 7 '-' || SUBSTR(v_phone_no,7); 8 END format_phone; 9 /

passing input as phone number and getting substr of the phone number.Note: As functions should only return a single value, you should not declare OUT and IN OUT parameters for a function.

63. What is p-code?

P-code is the compiled form of the source code of a subprogram.

64. Difference between function and procedure?

A procedure containing one OUT parameter can be rewritten as a function containing a RETURN statement.Ex- of a user defined function:

FUNCTION tax (v_value IN NUMBER) RETURN NUMBERISBEGIN RETURN (v_value * .08);END tax;Procedure Function1. Execute as a PL/SQL statement Invoke as part of an expression 2. No RETURN datatype Must contain a RETURN datatype3. Can return none, one or many values Must return a single value

65. Coordination properties for master detail relation ?ImmediateDeferred with AutoqueryDeferred without Autoquery

66. Relational Properties for master detail relation ?

Isolated,non-isolated,cascading.

67. Triggers for master detail relation? How they change with realtional properties.

68. Procedures for master detail relation ?

69. Signifance of ‘Prevent masterless operation’?

70. Types of form triggers with example?

71. Diff between Procedure and a function?

72. What is dynamic sql? Package used for that and syntax?73. Diff between sql and sql* commands?

74. What are the different data sources of a block?

Data Source Query DML

Table YES YESView YES YES

FROM Clause YES NO

Procedure-Reference Cursor YES NO

Procedure-Table of Records YES YES

Transactional. Trigger YES YES

Object Table YES YES

Object Column –here table selected is the object table but column selected will have object datatype.

YES YES

Reference Lookup – here table selected will have a reference column whose attributes will be selected to create a ref lookup block.

YES NO

75. Creating an Object Table,Object column and reference column?

The syntax below creates an object table based on an object type:

CREATE TYPE aa_class_t AS OBJECT(department VARCHAR2(20), course_id NUMBER(4), credit_hours NUMBER(1));

CREATE TABLE aa_classes OF aa_class_t;

CREATE TABLE aa_assignments(student_id NUMBER(5), class aa_class_t); -- this is an object column with attributes (department ,course_id ,credit_hours )

CREATE TABLE aa_schedules(student_id NUMBER(5), class REF aa_class_t);

In the data block wizard, the REF column name (CLASS) appears twice in the column selection list. It appears once as a heading for the referenced object’s attributes. It then appears again as a pointer, and is a selectable column.

76. Types of record groups?

Query record Group –Design time & run time ----based on select stmt. Non-Query record group –Run time ----not based on select stmt. Static record group -- Design time ---- not based on select stmt.

77. New PL/SQL8 Scalar Datatypes:

• NCHAR stores fixed-length (blank-padded if necessary) NLS character data. How the data is represented internally depends on the national character set, which might use a fixed-width encoding such as US7ASCII or a variable-width encoding such as JA16SJIS.• NVARCHAR2 stores variable-length NLS character data. How the data is represented internally depends on the national character set, which might use a fixed-width encoding such as WE8EBCDIC37C or a variable-width encoding such as JA16DBCS. • SIGNTYPE lets you restrict an integer variable to the values -1, 0, and 1, which is useful in programming tri-state logic. • FLOAT is a subtype of NUMBER. However, you cannot specify a scale for FLOAT variables. You can only specify a binary precision. • NATURALN is like subtype NATURAL, but prevents the assignment of NULL.• POSITIVEN is like subtype POSITIVE, but prevents the assignment of NULL.• PLS_INTEGER stores signed integers. Its magnitude range is -2147483647 .. 2147483647. PLS_INTEGER values require less storage than NUMBER values. Also, PLS_INTEGER operations use machine arithmetic, so they are faster than NUMBER and BINARY_INTEGER operations, which use library arithmetic.

Besides the database character set, which is used for identifiers and source code, PL/SQL8 now supports a second character set called the national character set, which is used for NLS data. The PL/SQL datatypes NCHAR and NVARCHAR2 allow you to store character strings formed from the national character set.

78.Example of FORMS_DDL, FORM_SUCCESS, DBMS_ERROR_CODE & DBMS_ERROR_TEXT

FORMS_DDL (‘BEGIN ‘ || p_proc_name ||‘; END; ‘);IF not FORM_SUCCESS THEN

handle_server_error(DBMS_ERROR_CODE, DBMS_ERROR_TEXT);

END IF;79. In Apps11i diff between a standalone form and a function ?

A form can show different output each time if it is stored as a function by giving different options in the options field while registration.

80. Unix commands ?

Important Questions in Oracle, Developer /2000(Form 4.5 and Reports 2.5)

Oracle

1) What is the Back ground processes in Oracle and what are they.1) This is one of the most frequently asked questions. There are basically 9 Processes but in a General system we need to mention the first five background processes. They do the house keeping activities for the Oracle and are common in any system.The various background processes in oracle are a) Data Base Writer (DBWR) :: Data Base Writer Writes Modified blocks from Database buffer cache to Data Files. This is required since the data is not written whenever a transaction is commited.b) LogWriter (LGWR) :: LogWriter writes the redo log entries to disk. Redo Log data is generated in redo log buffer of SGA. As transaction commits and log buffer fills, LGWR writes log entries into a online redo log file.c) System Monitor (SMON) :: The System Monitor performs instance recovery at instance startup. This is useful for recovery from system failured) Process Monitor (PMON) :: The Process Monitor performs process recovery when user Process fails. Pmon Clears and Frees resources that process was using.e) CheckPoint (CKPT) :: At Specified times, all modified database buffers in SGA are written to data files by DBWR at Checkpoints and Updating all data files and control files of database to indicate the most recent checkpointf) Archieves (ARCH) :: The Archiver copies online redo log files to archival storal when they are busy.g) Recoveror(RECO) :: The Recoveror is used to resolve the distributed transaction in networkh) Dispatcher (Dnnn) :: The Dispatcher is useful in Multi Threaded Architecturei) Lckn :: We can have upto 10 lock processes for inter instance locking in parallel sql.

2) How many types of Sql Statements are there in Oracle2) There are basically 6 types of sql statements. They area) Data Definition Language (DDL): The DDL statements define and maintain objects and drop objects.b) Data Manipulation Language (DML): The DML statements manipulate database data.c) Transaction Control Statements: Manage change by DMLd) Session Control: Used to control the properties of current session enabling and disabling roles and changing .e.g: Alter Statements, Set Rolee) System Control Statements: Change Properties of Oracle Instance .e.g:: Alter Systemf) Embedded Sql: Incorporate DDL, DML and T.C.S in Programming Language .e.g:: Using the Sql Statements in languages such as 'C', Open, Fetch, execute and close

3) What is a Transaction in Oracle?

3) A transaction is a Logical unit of work that compromises one or more SQL Statements executed by a single User. According to ANSI, a transaction begins with first executable statement and ends when it is explicitly commited or rolled back.

4) Key Words Used in Oracle?4) The Key words that are used in Oracle are :: a) Committing: A transaction is said to be commited when the transaction makes permanent changes resulting from the SQL statements. b) Rollback: A transaction that retracts any of the changes resulting from SQL statements in Transaction. c) SavePoint: For long transactions that contain many SQL statements, intermediate markers or savepoints are declared. Savepoints can be used to divide a transaction into smaller points.d) Rolling Forward: Process of applying redo log during recovery is called rolling forward. e) Cursor: A cursor is a handle (name or a pointer) for the memory associated with a specific statement. A cursor is basically an area allocated by Oracle for executing the Sql Statement. Oracle uses an implicit cursor statement for Single row query and Uses Explicit cursor for a multi row query.f) System Global Area (SGA): The SGA is a shared memory region allocated by the Oracle that contains Data and control information for one Oracle Instance. It consists of Database Buffer Cache and Redo log Buffer.g) Program Global Area (PGA): The PGA is a memory buffer that contains data and control information for server process.g) Database Buffer Cache: Database Buffer of SGA stores the most recently used blocks of database data. The set of database buffers in an instance is called Database Buffer Cache.h) Redo log Buffer :: Redo log Buffer of SGA stores all the redo log entries. i) Redo Log Files :: Redo log files are set of files that protect altered database data in memory that has not been written to Data Files. They are basically used for backup when a database crashes.j) Process :: A Process is a 'thread of control' or mechanism in Operating System that executes series of steps.

5) What are Procedure, functions and Packages?5) Procedures and functions consist of set of PL/SQL statements that are grouped together as a unit to solve a specific problem or perform set of related tasks. Procedures do not return values while Functions return one ValuePackages :: Packages Provide a method of encapsulating and storing related procedures, functions, variables and other Package Contents

6) What are Database Triggers and Stored Procedures?6) Database Triggers :: Database Triggers are Procedures that are automatically executed as a result of insert in, update to, or delete from table. Database triggers have the values old and new to denote the old value in the table before it is deleted and the new indicated the new value that will be used. DT is useful for implementing complex business rules, which cannot be enforced using the integrity rules. We can have the trigger as Before trigger or After Trigger and at Statement or Row level.e.g:: operations insert, update ,delete 3

before ,after 3*2 A total of 6 combinations At statement level (once for the trigger) or row level( for every execution ) 6 * 2 A total of 12. Thus a total of 12 combinations are there and the restriction of usage of 12 triggers has been lifted from Oracle 7.3 Onwards.Stored Procedures :: Stored Procedures are Procedures that are stored in Compiled form in the database. The advantage of using the stored procedures is that many users can use the same procedure in compiled and ready to use format.

7) How many Integrity Rules are there and what are they?7) There are Three Integrity Rules. They are as follows ::a) Entity Integrity Rule :: The Entity Integrity Rule enforces that the Primary key cannot be Nullb) Foreign Key Integrity Rule :: The FKIR denotes that the relationship between the foreign key and the primary key has to be enforced. When there is data in Child Tables the Master tables cannot be deleted.c) Business Integrity Rules :: The Third Integrity rule is about the complex business processes which cannot be implemented by the above 2 rules.

8) What are the Various Master and Detail Relation ships?8) The various Master and Detail Relationship area) NonIsolated :: The Master cannot be deleted when a child is existingb) Isolated :: The Master can be deleted when the child is existingc) Cascading :: The child gets deleted when the Master is deleted.

9) What are the Various Block Coordination Properties?9) The various Block Coordination Properties are a) Immediate Default Setting. The Detail records are shown when the Master Record are shown.b) Differed with Auto QueryOracle Forms defer fetching the detail records until the operator navigates to the detail block.c) Differed with No Auto QueryThe operator must navigate to the detail block and explicitly execute a query

10) What are the Different Optimization Techniques?10) The Various Optimization techniques are a) Execute Plan :: we can see the plan of the query and change it accordingly based on the indexesb) Optimizer_hint ::set_item_property('DeptBlock',OPTIMIZER_HINT,'FIRST_ROWS');Select /*+ First_Rows */ Deptno,Dname,Loc,Rowid from deptwhere (Deptno > 25)c) Optimize_Sql ::By setting the Optimize_Sql = No, Oracle Forms assigns a single cursor for all SQL statements. This slow downs the processing because for every time the SQL must be parsed whenever they are executed.f45run module = my_firstform userid = scott/tiger optimize_sql = No

d) Optimize_Tp :: By setting the Optimize_Tp= No, Oracle Forms assigns separate cursor only for each query SELECT statement. All other SQL statements reuse the cursor.f45run module = my_firstform userid = scott/tiger optimize_Tp = No

11) How do u implement the If statement in the Select Statement?11) We can implement the if statement in the select statement by using the Decode statement.e.g select DECODE (EMP_CAT,'1','First','2','Second'Null);Here the Null is the else statement where null is done .

12) How many types of Exceptions are there12) There are 2 types of exceptions. They area) System Exceptionse.g. When no_data_foiund, When too_many_roiwsb) User Defined Exceptionse.g. My_exception exceptionWhen My_exception then

13) What are the inline and the precompiler directives?13) The inline and precompiler directives detect the values directly

14) How do you use the same lov for 2 columns14) We can use the same lov for 2 columns by passing the return values in global values and using the global values in the code

15) How many minimum groups are required for a matrix report15) The minimum number of groups in matrix report are 4

16) What is the difference between static and dynamic lov16) The static lov contains the predetermined values while the dynamic lov contains values that come at run time

17) What are snap shots and views?17) Snapshots are mirror or replicas of tables. Views are built using the columns from one or more tables. The Single Table View can be updated but the view with multi table cannot be updated

18) What are the OOPS concepts in Oracle.18) Oracle does implement the OOPS concepts. The best example is the Property Classes. We can categories the properties by setting the visual attributes and then attach the property classes for theobjects. OOPS supports the concepts of objects and classes and we can consider the property classes as classes and the items as objects

19) What is the difference between candidate key, unique key and primary key

19) Candidate keys are the columns in the table that could be the primary keys and the primary keyis the key that has been selected to identify the rows. Unique key is also useful for identifying the distinct rows in the table.

20)What is concurrency20) Concurrency is allowing simultaneous access of same data by different users. Locks useful for accessing the database area) Exclusive The exclusive lock is useful for locking the row when an insert, update or delete is being done. This lock should not be applied when we do only select from the row.b) Share lockWe can do the table as Share_Lock as many share_locks can be put on the same resource.

21) Privileges and Grants21) Privileges are the right to execute a particular type of SQL statements.e.g :: Right to Connect, Right to create, Right to resourceGrants are given to the objects so that the object might be accessed accordingly. The grant has to begiven by the owner of the object.

22)Table Space, Data Files, Parameter File, Control Files22)Table Space :: The table space is useful for storing the data in the database. When a database is created two table spaces are created.a) System Table space :: This data file stores all the tables related to the system and dba tablesb) User Table space :: This data file stores all the user related tables We should have separate table spaces for storing the tables and indexes so that the access is fast.Data Files :: Every Oracle Data Base has one or more physical data files. They store the data for the database. Every datafile is associated with only one database. Once the Data file is created the size cannot change. To increase the size of the database to store more data we have to add data file. Parameter Files :: Parameter file is needed to start an instance. A parameter file contains the list of instance configuration parameters e.g.::db_block_buffeirs = 500db_name = ORA7db_domain = u.s.acme langControl Files :: Control files record the physical structure of the data files and redo log filesThey contain the Db name, name and location of dbs, data files ,redo log files and time stamp.

23) Physical Storage of the Data23) The finest level of granularity of the data base are the data blocks. Data Block :: One Data Block correspond to specific number of physical database space

Extent :: Extent is the number of specific number of contiguous data blocks.Segments :: Set of Extents allocated for Extents. There are three types of Segmentsa) Data Segment :: Non Clustered Table has data segment data of every table is stored incluster data segmentb) Index Segment :: Each Index has index segment that stores datac) Roll Back Segment :: Temporarily store 'undo' information

24) What are the Pct Free and Pct Used?24) Pct Free is used to denote the percentage of the free space that is to be left when creating a table. Similarly Pct Used is used to denote the percentage of the used space that is to be used when creating a tableeg.:: Pctfree 20, Pictused 40

25) What is Row Chaining25) The data of a row in a table may not be able to fit the same data block. Data for row is stored in a chain of data blocks .

26) What is a 2 Phase Commit26) Two Phase commit is used in distributed data base systems. This is useful to maintain the integrity of the database so that all the users see the same values. It contains DML statements or Remote Procedural calls that reference a remote object. There are basically 2 phases in a 2 phase commit.a) Prepare Phase :: Global coordinator asks participants to prepareb) Commit Phase :: Commit all participants to coordinator to Prepared, Read only or abort Reply

27) What is the difference between deleting and truncating of tables27) Deleting a table will not remove the rows from the table but entry is there in the database dictionary and it can be retrieved But truncating a table deletes it completely and it cannot be retrieved.

28) What are mutating tables28) When a table is in state of transition it is said to be mutating. eg :: If a row has been deleted then the table is said to be mutating and no operations can be done on the table except select.

29) What are Codd Rules29) Codd Rules describe the ideal nature of a RDBMS. No RDBMS satisfies all the 12 codd rules and Oracle Satisfies 11 of the 12 rules and is the only Rdbms to satisfy the maximum number of rules.

30) What is Normalization30) Normalization is the process of organizing the tables to remove the redundancy. There are mainly 5 Normalization rules.a) 1 Normal Form :: A table is said to be in 1st Normal Form when the attributes are atomic

b) 2 Normal Form :: A table is said to be in 2nd Normal Form when all the candidate keys are dependant on the primary keyc) 3rd Normal Form :: A table is said to be third Normal form when it is not dependant transitively

31) What is the Difference between a post query and a pre query31) A post query will fire for every row that is fetched but the pre query will fire only once.

32) Deleting the Duplicate rows in the table32) We can delete the duplicate rows in the table by using the Rowid33) Can U disable database trigger? How? 33) Yes. With respect to table ALTER TABLE TABLE [ DISABLE all_trigger ]34) What is pseudo columns ? Name them?

34) A pseudo column behaves like a table column, but is not actually stored in the table. You can select from pseudo columns, but you cannot insert, update, or delete their values. This section describes these pseudo columns: * CURRVAL * NEXTVAL * LEVEL * ROWID * ROWNUM

35) How many columns can table have? The number of columns in a table can range from 1 to 254.

36) Is space acquired in blocks or extents ?

In extents .

37) what is clustered index? In an indexed cluster, rows are stored together based on their cluster key values . Can not applied for HASH.

38) what are the data types supported By oracle (INTERNAL)? Varchar2, Number, Char , MLSLABEL.

39 ) What are attributes of cursor? %FOUND , %NOTFOUND , %ISOPEN,%ROWCOUNT

40) Can you use select in FROM clause of SQL select ? Yes.

Forms 4.5 Questions

1) Which trigger are created when master -detail relation?1) master delete property

* NON-ISOLATED (default)

a) on check delete masterb) on clear detailsc) on populate details

* ISOLATED

a) on clear detailsb) on populate details

* CASCADE

a) per-deleteb) on clear detailsc) on populate details

2) which system variables can be set by users?2)SYSTEM.MESSAGE_LEVELSYSTEM.DATE_THRESHOLDSYSTEM.EFFECTIVE_DATESYSTEM.SUPPRESS_WORKING

3) What are object group?3)An object group is a container for a group of objects. You define an object group when you want to package related objects so you can copy or reference them in another module.

4) What are referenced objects?4)Referencing allows you to create objects that inherit their functionality and appearance from other objects.

Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object.

5) Can you store objects in library?5)Referencing allows you to create objects that inherit their functionality and appearance from other objects. Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object.

6) Is forms 4.5 object oriented tool ? why?6)yes , partially. 1) PROPERTY CLASS - inheritance property 2) OVERLOADING : procedures and functions.

7) Can you issue DDL in forms?7)yes, but you have to use FORMS_DDL.Referencing allows you to create objects that inherit their functionality and appearance from other objects. Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object. Any string expression up to 32K: ·a literal · an expression or a variable representing the text of a block of dynamically created PL/SQL code · a DML statement or · a DDL statement

Restrictions:The statement you pass to FORMS_DDL may not contain bind variable references in the string, but the

values of bind variables can be concatenated into the string before passing the result to FORMS_DDL.

8) What is SECURE property?8)- Hides characters that the operator types into the text item. This setting is typically used for password protection.

9 ) What are the types of triggers and how the sequence of firing in text item9) Triggers can be classified as Key Triggers, Mouse Triggers ,Navigational Triggers. Key Triggers :: Key Triggers are fired as a result of Key action. e.g :: Key-next-field, Key-up, Key-DownMouse Triggers :: Mouse Triggers are fired as a result of the mouse navigation. e.g. When-mouse-button-pressed, when-mouse-double clicked, etcNavigational Triggers :: These Triggers are fired as a result of Navigation. E.g : Post-Text-item, Pre-text-item.We also have event triggers like when –new-form-instance and when-new-block-instance.We cannot call restricted procedures like go_to(‘my_block.first_item’) in the Navigational triggersBut can use them in the Key-next-item.The Difference between Key-next and Post-Text is an very important question. The key-next is fired as a result of the key action while the post text is fired as a result of the mouse movement. Key next will not fire unless there is a key event.The sequence of firing in a text item are as follows :: a) pre - text b) when new item c) key-next d) when validate e) post text

10 ) Can you store pictures in database? How?10)Yes , in long Raw datatype.

11) What are property classes? Can property classes have trigger?11) Property class inheritance is a powerful feature that allows you to quickly define objects that conform to your own interface and functionality standards. Property classes also allow you to make global changes to applications quickly. By simply changing the definition of a property class, you can change the definition of all objects that inherit properties from that class. Yes . All type of triggers .

* 12 a) If you have property class attached to an item and you have same trigger written for the item. Which will fire first?

12)Item level trigger fires , If item level trigger fires, property level trigger won't fire. Triggers at the lowest level are always given the first preference. The item level trigger fires first and then the block and then the Form level trigger. 13) What are record groups ? * Can record groups created at run-time?13)A record group is an internal Oracle Forms data structure that has a column/row framework similar to a database table. However, unlike database tables, record groups are separate objects that belong to the form module in which they are defined. A record group can have an unlimited number of columns of type CHAR, LONG, NUMBER, or DATE provided that the total number of columns does not exceed 64K. Record group column names cannot exceed 30 characters.Programmatically, record groups can be used whenever the functionality offered by a two-dimensional array of multiple data types is desirable. TYPES OF RECORD GROUP:Query Record Group A query record group is a record group that has an associated SELECT statement. The columns in a query record group derive their default names, data types, and lengths from the database columns referenced in the SELECT statement. The records in a query record group are the rows retrieved by the query associated with that record group. Non-query Record Group A non-query record group is a group that does not have an associated query, but whose structure and values can be modified programmatically at runtime. Static Record GroupA static record group is not associated with a query; rather, you define its structure and row values at design time, and they remain fixed at runtime.

14) What are ALERT? 14)An ALERT is a modal window that displays a message notifiying operator of some application condition.

15) Can a button have icon and label at the same time ?15) -NO

16) What is mouse navigate property of button?16)When Mouse Navigate is True (the default), Oracle Forms performs standard navigation to move the focus to the item when the operator activates the item with the mouse.

When Mouse Navigate is set to False, Oracle Forms does not perform navigation (and the resulting validation) to move to the item when an operator activates the item with the mouse.

17) What is FORMS_MDI_WINDOW?

17) forms run inside the MDI application window. This property is useful for calling a form from another one.

18) What are timers ? when when-timer-expired does not fire? 18) The When-Timer-Expired trigger can not fire during trigger, navigation, or transaction processing.

19 ) Can object group have a block? 19)Yes , object group can have block as well as program units.

20) How many types of canvases are there.20)There are 2 types of canvases called as Content and Stack Canvas. Content canvas is the default and the one that is used mostly for giving the base effect. Its like a plate on which we add items and stacked canvas is used for giving 3 dimensional effect.

The following questions might not be asked in an Average Interview and could be asked when the Interviewer wants to trouble u and go deeppppppppppppp……He cannot go further…..

1) What are user-exits?1) It invokes 3GL programs.

2) Can you pass values to-and-fro from foreign function ? how ? 2) Yes . You obtain a return value from a foreign function by assigning the return value to an Oracle Forms variable or item. Make sure that the Oracle Forms variable or item is the same data type as the return value from the foreign function.After assigning an Oracle Forms variable or item value to a PL/SQL variable, pass the PL/SQL variable as a parameter value in the PL/SQL interface of the foreign function. The PL/SQL variable that is passed as a parameter must be a valid PL/SQL data type; it must also be the appropriate parameter type as defined in the PL/SQL interface.

3) What is IAPXTB structure ?3) The entries of Pro * C and user exits and the form which simulate the proc or user_exit are stored in IAPXTB table in d/b.

4) Can you call WIN-SDK thruo' user exits?4) YES.

5) Does user exits supports DLL on MSWINDOWS ?

5) YES .

6) What is path setting for DLL?6) Make sure you include the name of the DLL in the FORMS45_USEREXIT variable of the ORACLE.INI file, or rename the DLL to F45XTB.DLL. If you rename the DLL to F45XTB.DLL, replace the existing F45XTB.DLL in the \ORAWIN\BIN directory with the new F45XTB.DLL.

7) How is mapping of name of DLL and function done?7) The dll can be created using the Visual C++ / Visual Basic Tools and then the dll is put in the path that is defined the registry.

8) what is precompiler?8) It is similar to C precompiler directives.

9) Can you connect to non - oracle data source ? How?9) Yes .

10 ) what are key-mode and locking mode properties? level ?10) Key Mode : Specifies how oracle forms uniquely identifies rows in the database. This is property includesfor application that will run against NON-ORACLE data sources .Key setting unique (default.)

dateablen-updateable.

Locking mode : Specifies when Oracle Forms should attempt to obtain database locks on rows that correspond to queried records in the form. a) immediate b) delayed

11) What are savepoint mode and cursor mode properties ? level?11) Specifies whether Oracle Forms should issue savepoints during a session. This property is included primarily for applications that will run against non-ORACLE data sources. For applications that will run against ORACLE, use the default setting. Cursor mode - define cursor state across transaction Open/close.

12) Can you replace default form processing ? How ?

13) What is transactional trigger property?13) Identifies a block as transactional control block. i.e. non - database block that oracle forms should manage as transactional block.(NON-ORACLE data source) default - FALSE.

14) What is OLE automation ? 14) OLE automation allows an OLE server application to expose a set of commands and functions that can be

invoked from an OLE container application. OLE automation provides a way for an OLE container application to use the features of an OLE server application to manipulate an OLE object from the OLE container environment. (FORMS_OLE)

15) What does invoke built-in do?15) This procedure invokes a method.Syntax:PROCEDURE OLE2.INVOKE (object obj_type, method VARCHAR2, list list_type := 0);Parameters:object Is an OLE2 Automation Object.method Is a method (procedure) of the OLE2 object.list Is the name of an argument list assigned to the OLE2.CREATE_ARGLIST function.

16) What are OPEN_FORM,CALL_FORM,NEW_FORM? diff?16) CALL_FORM : It calls the other form. but parent remains active, when called form completes the operation , it releases lock and control goes back to the calling form.When you call a form, Oracle Forms issues a savepoint for the called form. If the CLEAR_FORM function causes a rollback when the called form is current, Oracle Forms rolls back uncommitted changes to this savepoint.OPEN_FORM : When you call a form, Oracle Forms issues a savepoint for the called form. If the CLEAR_FORM function causes a rollback when the called form is current, Oracle Forms rolls back uncommitted changes to this savepoint.NEW_FORM : Exits the current form and enters the indicated form. The calling form is terminated as the parent form. If the calling form had been called by a higher form, Oracle Forms keeps the higher call active and treats it as a call to the new form. Oracle Forms releases memory (such as database cursors) that the terminated form was using. Oracle Forms runs the new form with the same Runform options as the parent form. If the parent form was a called form, Oracle Forms runs the new form with the same options as the parent form.

17 ) What is call form stack?17) When successive forms are loaded via the CALL_FORM procedure, the resulting module hierarchy is known as the call form stack.

18) Can u port applications across the platforms? how?

18) Yes we can port applications across platforms. Consider the form developed in a windows system. The form would be generated in unix system by using f45gen my_form.fmb scott/tiger

GUI

1) What is a visual attribute?1) Visual attributes are the font, color, and pattern properties that you set for form and menu objects that appear in your application's interface.

2) Diff. between VAT and Property Class? imp2)Named visual attributes define only font, color, and pattern attributes; property classes can contain these and any other properties. You can change the appearance of objects at runtime by changing the named visual attribute programmatically; property class assignment cannot be changed programmatically. When an object is inheriting from both a property class and a named visual attribute, the named visual attribute settings take precedence, and any visual attribute properties in the class are ignored.

3 ) Which trigger related to mouse?3) When-Mouse-Click When-Mouse-DoubleClick When-Mouse-Down When-Mouse-Enter When-Mouse-Leave When-Mouse-Move When-Mouse-Up

4) What is Current record attribute property?4) Specifies the named visual attribute used when an item is part of the current record.Current Record Attribute is frequently used at the block level to display the current row in a multi-record If you define an item-level Current Record Attribute, you can display a pre-determined item in a special color when it is part of the current record, but you cannot dynamically highlight the current item, as the input focus changes.

5) Can u change VAT at run time?5) Yes. You can programmatically change an object's named visual attribute setting to change the font, color, and pattern of the object at runtime.

6) Can u set default font in forms?6) Yes. Change windows registry(regedit). Set form45_font to the desired font.

7) Can u have OLE objects in forms?7) Yes.

8) Can u have VBX and OCX controls in forms ?8) Yes.

9) What r the types of windows (Window style)?9) Specifies whether the window is a Document window or a Dialog window.10) What is OLE Activation style property?10) Specifies the event that will activate the OLE containing item.

11) Can u change the mouse pointer ? How?11) Yes. Specifies the mouse cursor style. Use this property to dynamically change the shape of the cursor.

Reports 2.5

1) How many types of columns are there and what are they1) Formula columns :: For doing mathematical calculations and returning one value

Summary Columns :: For doing summary calculations such as summations etc.Place holder Columns :: These columns are useful for storing the value in a variable

2) Can u have more than one layout in report2) It is possible to have more than one layout in a report by using the additional layout

option in the layout editor.

3) Can u run the report with out a parameter form3) Yes it is possible to run the report without parameter form by setting the PARAM

value to Null

4) What is the lock option in reports layout4) By using the lock option we cannot move the fields in the layout editor outside the

frame. This is useful for maintaining the fields .

5) What is Flex5) Flex is the property of moving the related fields together by setting the flex property on

6) What are the minimum number of groups required for a matrix report6) The minimum of groups required for a matrix report are 4

Most Frequently Asked Questions

What are your strengths and weaknesses? Tell me about yourself. What are your team-player qualities? Give examples. Of the courses you have had at college which courses have you enjoyed the most? What is your GPA? How do you feel about it? Does it reflect your abilities? How have your educational and work experiences prepared you for this position? What work experiences have been most valuable to you and why? What have the experiences on your resume taught you about managing and working with people? Of the hobbies and interests listed on your resume what is your favorite and tell me why? Where do you see yourself in five years? What goals have you set for yourself? How are you planning to achieve them? To what do you owe your present success? Why should I hire you? What makes you think you can handle this position? What is your most significant accomplishment to date? Why do you want to work here? Describe a leadership role of yours and tell why you committed your time to it. In a particular leadership role you had, what was your greatest challenge? Give me an example of an idea that has come to you and what you did with it? Give me an example of a problem you solved and the process you used? Give me an example of the most creative project that you have worked on. Tell me about a project you initiated? Describe the project or situation that best demonstrates your analytical abilities? Since attending college, what is the toughest decision that you have had to make? Tell me about your most difficult decision and how did you go about making it? What types of situations put you under pressure, and how do you deal with pressure? Give me a situation in which you failed, and how you handled it? Why are you interested in our organization? What type of position are you seeking? Where do you think your interest in this career comes from? What industry besides this one are you looking into? Why have you chosen this particular profession? What interests you about this job? What challenges are you looking for in a position? What can you contribute to this company? What motivates you? What turns you off? If I asked the people who know you well to describe you, what three words would they use? If I asked the people who know you for one reason why I shouldn't hire you what would they say? When you take on a project do you like to attack the project in a group of individually? Describe the type of manager you prefer. Tell me about a team project of which you are particularly proud and your contribution? Describe a situation where you had to work with someone who was difficult, how did you handle it? What type of work environment appeals to you most? With which other companies are you interviewing? What charactersitics do you think are important for this position? Why do you feel that this company will be a career for you rather than a job? Name two management skills that you think you have? What characteristics are most important in a good manager? How have you displayed one of them? Why did you choose this college and how did you arrive at this decision? What factors did you consider in choosing your major?

Describe how your favorite course has contributed your career interests? Since you have been at college, what is it that you are proudest of? How have you changed personally since starting college? What has been your greatest challenge? If you could change a decision you made while at college what would you change and why? Why did you choose the campus involvements you did? What did you gain? What did you

contribute?

Questions You Can Ask the Interviewer:

Ask about the information you researched. Describe my job duties. Is this a newly created position? What are the companies short and long term goals? What do you like most about working for this company? What is a typical day like for you? To whom would I report? Whom will I supervise? Tell me about the training program I will experience. What is the company's promotional policy? With whom will I be working most closely? When can I expect to hear from you?

DataBase Assignment

Question 1.

Record Tracking

In any competitive event there are records that stand and records that are broken.The event categories contains the world record and commonwealth record figures for all events as this meeting.As the events have their heats and finals run some of the records get broken with new records being set. Your task in this question is to write PL/SQL program to determine who ,if anyone,broke records during the meeting .First you will need to create a table to store history into.Initially this new table will contain the current world and commonwealth records for each event category.Then,as the races are completed ,each change to either the commonwealth or the world record time should be recorded by adding a new row to the table. Once completed your program will have recorded, in the table you create, the initial time for each record and all subsequent changes to the records. Note that only the first person to finish a race can break a record since anyone finishing after them will have a slower time than the record they just set.

The table you create to store the history of the records should have columns for the event description, the gender of competitors, the name of the competitor who set the record, the record type (either W or C for the

commonwealth), the date the record was set, and the record time. For records which existed prior to the meeting (which are stored in the Event Categories table) the name, and date of the record will be null.

You must report the record history in order of the event description, within event description sort by gender, within gender sort by record type,within record type sort in the descending order of time.

Submit the following: The create table statement you used to create your table for storing the record history. The PL/SQL code you used to determine the records. The SQL code you used to output the table of resulting record history. The actual output from the execution of the SQL statement.

No table joins are permitted.Your procedure should have multiple cursors and pass parameters.Examples of parameter passing are included in the study guide and will also appear in lectures slides during the semester.

Question 2

Produce a PL/SQL stored procedure as follows:

The stored procedure should accept an input parameter of competitor ID.For the competitor selected,the following information should be presented on the screen.

Competitor Name

For each race in which the competitor has completed,the following information:

Event Number Result Time Position

No table joing are permitted.Your procedure should have multiple cursors and pass parameters.

Submit the following for both PL/SQL questions: The PL/SQL code printed out. The actual output from the execution of the program.

The Tables for the Database

CountriesThe countries listed in the Countries table,described below,include all of the countries that participate in the Commonwealth Games,however,not all of these countries have representatives at this competition.

Create table Countries(CountryID varchar2(3) not null,CountryName varchar2(40) not null,CONSTRAINT Countries_pk primary key ( countryID));

The CountryID represents the three letter abbreviation used fo rthe country in the Commonwealth Games competition.The country name is the name usually used when referring to the country.

Competitors

The competitors table contains a list of the competitors who may or may not compete in these games.Not all competitors in the competitors table actually compete in the games.

Create table Competitors(CompetitorNo number (4) not null,Name varchar2(40) not null,CountryID varchar2(3),DateBirth date,Gender char(1),CONSTRAINT Competitors_pk primary key (competitorNO));

The countryID represents a countryID from the Countries table and acts as foreign key into that table.Gender is a single character field that contains a code representing the gender of the competitor.This column will contain M for male competitors or F for female competitors.

Event Categories

The EventCategories table contains the various categories of events that are contested at the games.For example,one such event category is the Men’s 100m Backstroke.Notice that an event category consists of an event description and a gender.Also recorded in this table are the world and commonwealth record time for the particular event as they stood just prior to the competion.

create table EventCategories (EventCatNo number(2) not null,EventDescr varchar2(30) not null,Gender char(1),WorldRecord number(8,4),CommonwealthRecord number(8,4),CONSTRAINT EventCategories_pk primary key (EventCatNo));

Events

The Events table contains the particular events being contested at the games.In this table the events are actual races, which are ither eheats or finals and have a scheduled start time.

create table Events(EventNo number(4) not null,EventCatNo number(2) not null,EventType char(1),StartTime date,CONSTRAINT Events_pk primary key (EventNo),CONSTRAINT Events_fk foreign key (EventCatNo) references EventCateogries (EventCatNo));

The EventNo column contains a unique integer used as the primary key for the event.The EventCatNo provides a foreign key into the event categories table and enables an association between the event and its details including the records.EventType is a single character coding which shows whether an event is a heat(H) or a final(f).

Entries

The Entries table associates a competitor with a particular event.It not only records the fact that the competitor has entered the event but also the resulting time that they have achieved, the lane that they were assigned and a flag to indicate whether or not they were disqualified.

Create table Entries(EventNo number(4) not null,CompetitorNo number(4) not null,Lane number(1),ResultTime number(8,4),Disqualified char(1),CONSTRAINT Entries_pk primary key (EventNo, competitorNo),CONSTRAINT Entries_Evts_fk foreign key (EventNo) references Events(EventNo), CONSTRAINT Entries_Comp_fk foreign key (competitotNo) references Competitors(CompetitorNo));

The EventNo column is a foreign key into the Events table.The competitorNo column provides a foreign key back to the competitors table.Disqualified contain a Y if the competitor has been disqualified and an N otherwise.A disqualified competitor is not eligible for any medals not are they able to break any records, regardless of the time they swim.

INDEX

1. Query for retrieving N highest paid employees FROM each Department.2. Query that will display the total no. of employees, and of that total the

number who were hired in 1980, 1981, 1982, and 1983. 3. Query for listing Deptno, ename, sal, SUM(sal in that dept).4. Matrix query to display the job, the salary for that job based on department

number, and the total salary for that job for all departments. 5. Nth Top Salary of all the employees. 6. Retrieving the Nth row FROM a table. 7. Tree Query. 8. Eliminate duplicates rows in a table. 9. Displaying EVERY Nth row in a table. 10. Top N rows FROM a table.11. COUNT/SUM RANGES of data values in a column. 12. For equal size ranges it might be easier to calculate it with

DECODE(TRUNC(value/range), 0, rate_0, 1, rate_1, ...).

13. Count different data values in a column. 14. Query to get the product of all the values of a column. 15. Query to display only the duplicate records in a table.16. Query for getting the following output as many number of rows in the table. 17. Function for getting the Balance Value. 18. Function for getting the Element Value. 19. SELECT Query for counting No of words.20. Function to check for a leap year.21. Query for removing all non-numeric. 22. Query for translating a column values to INITCAP. 23. Function for displaying Rupees in Words.24. Function for displaying Numbers in Words25. Query for deleting alternate even rows FROM a table. 26. Query for deleting alternate odd rows FROM a table. 27. Procedure for sending Email. 28. Alternate Query for DECODE function. 29. Create table adding Constraint to a date field to SYSDATE or 3 months later. 30. Query to list all the suppliers who r supplying all the parts supplied by

supplier 'S2'. 31. Query to get the last Sunday of any month.

32. Query to get all those who have no children themselves.

33. Query to SELECT last N rows FROM a table. 34. SELECT with variables. 35. Query to get the DB Name. 36. Getting the current default schema. 37. Query to get all the column names of a particular table. 38. Spool only the query result to a file in SQLPLUS. 39. Query for getting the current SessionID. 40. Query to display rows FROM m to n. 41. Query to count no. Of columns in a table. 42. Procedure to increase the buffer length. 43. Inserting an & symbol in a Varchar2 column. 44. Removing Trailing blanks in a spooled file. 45. Samples for executing Dynamic SQL Statements. 46. Differences between SQL and MS-Access. 47. Query to display all the children, sub children of a parent. 48. Procedure to read/write data from/to a text file. 49. Query to display random number between any two given numbers. 50. Time difference between two date columns. 51. Using INSTR and SUBSTR52. View procedure code 53. To convert signed number to number in oracle 54. Columns of a table55. Delete rows conditionally56. CLOB to Char 57. Change Settings 58. Double quoting a Single quoted String 59. Time Conversion 60. Table comparison 61. Running Jobs 62. Switching Columns 63. Replace and Round 64. First date of the year 65. Create Sequence 66. Cursors 67. Current Week 68. Create Query to restrict the user to a single row. 69. Query to get the first inserted record FROM a table. 70. Concatenate a column value with multiple rows. 71. Query to delete all the tables at once. 72. SQL Query for getting Orphan Records.

1. The following query retrieves "2" highest paid employees FROM each Department :

SELECT deptno, empno, salFROM emp eWHERE2 > ( SELECT COUNT(e1.sal) FROM emp e1 WHERE e.deptno = e1.deptno AND e.sal < e1.sal )ORDER BY 1,3 DESC;

Index

2. Query that will display the total no. of employees, and of that total the number who were hired in 1980, 1981, 1982, and 1983. Give appropriate column headings.

I am looking at the following output. We need to stick to this format.

Total 1980 1981 1982 1983----------- ------------ ------------ ------------- -----------14 1 10 2 1

SELECT COUNT (*), COUNT(DECODE(TO_CHAR (hiredate, 'YYYY'),'1980', empno)) "1980", COUNT (DECODE (TO_CHAR (hiredate, 'YYYY'), '1981', empno)) "1981",

COUNT (DECODE (TO_CHAR (hiredate, 'YYYY'), '1982', empno)) "1982", COUNT (DECODE (TO_CHAR (hiredate, 'YYYY'), '1983', empno)) "1983"

FROM emp;

Index

3. Query for listing Deptno, ename, sal, SUM(sal in that dept) : SELECT a.deptno, ename, sal, (SELECT SUM(sal) FROM emp b WHERE a.deptno = b.deptno) FROM emp aORDER BY a.deptno;

OUTPUT :=======DEPTNO ENAME SAL SUM (SAL)========= ======= ==== ========= 10 KING 5000 11725 30 BLAKE 2850 10900 10 CLARK 2450 11725 10 JONES 2975 11725 30 MARTIN 1250 10900 30 ALLEN 1600 10900 30 TURNER 1500 10900 30 JAMES 950 10900 30 WARD 2750 10900 20 SMITH 8000 33000 20 SCOTT 3000 33000 20 MILLER 20000 33000

Index

4. Create a matrix query to display the job, the salary for that job based on department number, and the total salary for that job for all departments, giving each column an appropriate heading.

The output is as follows - we need to stick to this format :

Job Dept 10 Dept 20 Dept 30 Total---------- --------------- ------------- ------------- ---------

ANALYST 6000 6000CLERK 1300 1900 950 4150MANAGER 2450 2975 2850 8275PRESIDENT 5000 5000SALESMAN 5600 5600

SELECT job "Job", SUM (DECODE (deptno, 10, sal)) "Dept 10", SUM (DECODE (deptno, 20, sal)) "Dept 20", SUM (DECODE (deptno, 30, sal)) "Dept 30", SUM (sal) "Total"

FROM empGROUP BY job ;

Index

5. 4th Top Salary of all the employees :

SELECT DEPTNO, ENAME, SAL FROM EMP AWHERE3 = (SELECT COUNT(B.SAL) FROM EMP BWHERE A.SAL < B.SAL) ORDER BY SAL DESC;

Index

6. Retrieving the 5th row FROM a table :

SELECT DEPTNO, ENAME, SAL FROM EMP WHERE ROWID = (SELECT ROWID FROM EMP WHERE ROWNUM <= 5

MINUS SELECT ROWID FROM EMP WHERE ROWNUM < 5)

Index

7. Tree Query :

Name Null? Type-------------------------------------------------------------------SUB NOT NULL VARCHAR2(4)SUPER VARCHAR2(4)PRICE NUMBER(6,2)

SELECT sub, super FROM partsCONNECT BY PRIOR sub = superSTART WITH sub = 'p1';

Index

8. Eliminate duplicates rows in a table :

DELETE FROM table_name A WHERE ROWID > ( SELECT min(ROWID) FROM table_name B WHERE A.col = B.col);

Index

9. Displaying EVERY 4th row in a table : (If a table has 14 rows, 4,8,12 rows will be selected)

SELECT *FROM empWHERE (ROWID,0) IN (SELECT ROWID, MOD(ROWNUM,4)

FROM emp);

Index

10. Top N rows FROM a table : (Displays top 9 salaried people)

SELECT ename, deptno, sal FROM (SELECT * FROM emp ORDER BY sal DESC) WHERE ROWNUM < 10;

Index

11. How does one count/sum RANGES of data values in a column? A value x will be between values y and z if GREATEST(x, y) = LEAST(x, z).

SELECT f2,

COUNT(DECODE(greatest(f1,59), least(f1,100), 1, 0)) "Range 60-100", COUNT(DECODE(greatest(f1,30), least(f1, 59), 1, 0)) "Range 30-59", COUNT(DECODE(greatest(f1,29), least(f1, 0), 1, 0)) "Range 00-29" FROM my_table GROUP BY f2;

Index

12. For equal size ranges it migth be easier to calculate it with DECODE(TRUNC(value/range), 0, rate_0, 1, rate_1, ...).

SELECT ename "Name", sal "Salary", DECODE( TRUNC(sal/1000, 0), 0, 0.0, 1, 0.1, 2, 0.2, 3, 0.3) "Tax rate"FROM emp;

13. How does one count different data values in a column?

COL NAME DATATYPE----------------------------------------DNO NUMBERSEX CHAR

SELECT dno, SUM(DECODE(sex,'M',1,0)) MALE, SUM(DECODE(sex,'F',1,0)) FEMALE,

COUNT(DECODE(sex,'M',1,'F',1)) TOTALFROM t1GROUP BY dno;

Index

14. Query to get the product of all the values of a column :

SELECT EXP(SUM(LN(col1))) FROM srinu;

Index

15. Query to display only the duplicate records in a table:

SELECT num FROM satyam GROUP BY numHAVING COUNT(*) > 1;

Index

16. Query for getting the following output as many number of rows in the table :

***************

SELECT RPAD(DECODE(temp,temp,'*'),ROWNUM,'*') FROM srinu1;

Index

17. Function for getting the Balance Value :

FUNCTION F_BALANCE_VALUE(p_business_group_id number, p_payroll_action_id number, p_balance_name varchar2, p_dimension_name varchar2) RETURN NUMBER ISl_bal number;l_defined_bal_id number;l_assignment_action_id number;BEGIN SELECT assignment_action_id

INTO l_assignment_action_id FROM pay_assignment_actions

WHEREassignment_id = :p_assignment_idAND payroll_action_id = p_payroll_action_id;

SELECT defined_balance_id INTO

l_defined_bal_id FROM pay_balance_types pbt, pay_defined_balances pdb, pay_balance_dimensions pbd WHERE pbt.business_group_id = p_business_group_id AND UPPER(pbt.balance_name) = UPPER(p_balance_name) AND pbt.business_group_id = pdb.business_group_id AND pbt.balance_type_id = pdb.balance_type_id AND UPPER(pbd.dimension_name) = UPPER(p_dimension_name) AND pdb.balance_dimension_id = pbd.balance_dimension_id; l_bal := pay_balance_pkg.get_value(l_defined_bal_id,l_assignment_action_id); RETURN (l_bal); exception

WHEN no_data_found THEN RETURN 0;

END;

Index

18. Function for getting the Element Value :

FUNCTION f_element_value( p_classification_name in varchar2, p_element_name in varchar2, p_business_group_id in number, p_input_value_name in varchar2, p_payroll_action_id in number, p_assignment_id in number ) RETURN number IS l_element_value number(14,2) default 0; l_input_value_id pay_input_values_f.input_value_id%type; l_element_type_id pay_element_types_f.element_type_id%type;BEGIN

SELECT DISTINCT element_type_idINTO l_element_type_idFROM pay_element_types_f pet,

pay_element_classifications pecWHERE pet.classification_id = pec.classification_idAND upper(classification_name) = upper(p_classification_name)AND upper(element_name) = upper(p_element_name)AND pet.business_group_id = p_business_group_id;

SELECT input_value_idINTO l_input_value_idFROM pay_input_values_fWHERE upper(name) = upper(p_input_value_name)AND element_type_id = l_element_type_id;

SELECT NVL(prrv.result_value,0) INTO l_element_value FROM pay_run_result_values prrv, pay_run_results prr,

pay_assignment_actions paa WHERE prrv.run_result_id = prr.run_result_id

AND prr.assignment_ACTION_ID = paa.assignment_action_id AND paa.assignment_id = p_assignment_id AND input_value_id = l_input_value_id

AND paa.payroll_action_id = p_payroll_action_id;

RETURN (l_element_value); exception

WHEN no_data_found THEN RETURN 0;

END;

Index

19. SELECT Query for counting No of words :

SELECT ename,NVL(LENGTH(REPLACE(TRANSLATE(UPPER(RTRIM(ename)),'ABCDEFGHIJKLMNOPQRSTUVWXYZ'' ',' @'),' ',''))+1,1) word_lengthFROM emp;

Explanation :

TRANSLATE(UPPER(RTRIM(ename)),'ABCDEFGHIJKLMNOPQRSTUVWXYZ'' ',' @') -- This will translate all the characters FROM A-Z including a single quote to a space. It will also translate a space to a @.

REPLACE(TRANSLATE(UPPER(RTRIM(ename)),'ABCDEFGHIJKLMNOPQRSTUVWXYZ'' ',' @'),' ','') -- This will replace every space with nothing in the above result.

LENGTH(REPLACE(TRANSLATE(UPPER(RTRIM(ename)),'ABCDEFGHIJKLMNOPQRSTUVWXYZ'' ',' @'),' ',''))+1 -- This will give u the count of @ characters in the above result.

Index

20. Function to check for a leap year :

CREATE OR REPLACE FUNCTION is_leap_year (p_date IN DATE) RETURN VARCHAR2 AS v_test DATE; BEGIN

v_test := TO_DATE ('29-Feb-' || TO_CHAR (p_date,'YYYY'),'DD-Mon-YYYY'); RETURN 'Y';

EXCEPTION WHEN OTHERS THEN

RETURN 'N'; END is_leap_year;

SQL> SELECT hiredate, TO_CHAR (hiredate, 'Day') weekday FROM emp WHERE is_leap_year (hiredate) = 'Y';

Index

21. Query for removing all non-numeric :

SELECT TRANSLATE(LOWER(ssn),'abcdefghijklmnopqrstuvwxyz- ','') FROM DUAL;

Index

22. Query for translating a column values to INITCAP :

SELECT TRANSLATE(INITCAP(temp),SUBSTR(temp, INSTR(temp,'''')+1,1), LOWER(SUBSTR(temp, INSTR(temp,'''')+1)))FROM srinu1;

Index

23. Function for displaying Rupees in Words :

CREATE OR REPLACE FUNCTION RUPEES_IN_WORDS(amt IN NUMBER) RETURN CHARIS amount NUMBER(10,2); v_length INTEGER := 0; v_num2 VARCHAR2 (50) := NULL; v_amount VARCHAR2 (50); v_word VARCHAR2 (4000) := NULL; v_word1 VARCHAR2 (4000) := NULL; TYPE myarray IS TABLE OF VARCHAR2 (255); v_str myarray := myarray (' thousand ', ' lakh ', ' crore ', ' arab ', ' kharab ', ' shankh ');BEGIN

amount := amt;IF ((amount = 0) OR (amount IS NULL)) THEN

v_word := 'zero';ELSIF (TO_CHAR (amount) LIKE '%.%') THEN

IF (SUBSTR (amount, INSTR (amount, '.') + 1) > 0) THEN v_num2 := SUBSTR (amount, INSTR (amount, '.') + 1); IF (LENGTH (v_num2) < 2) THEN v_num2 := v_num2 * 10; END IF;

v_word1 := ' AND ' || (TO_CHAR (TO_DATE (SUBSTR (v_num2, LENGTH (v_num2) - 1,2), 'J'), 'JSP' ))|| ' paise ';

v_amount := SUBSTR(amount,1,INSTR (amount, '.')-1);

v_word := TO_CHAR (TO_DATE (SUBSTR (v_amount, LENGTH (v_amount) - 2,3), 'J'), 'Jsp' ) || v_word; v_amount := SUBSTR (v_amount, 1, LENGTH (v_amount) - 3); FOR i in 1 .. v_str.COUNT LOOP EXIT WHEN (v_amount IS NULL); v_word := TO_CHAR (TO_DATE (SUBSTR (v_amount, LENGTH (v_amount) - 1,2), 'J'), 'Jsp' ) || v_str (i) || v_word; v_amount := SUBSTR (v_amount, 1, LENGTH (v_amount) - 2); END LOOP; END IF;

ELSE v_word := TO_CHAR (TO_DATE (SUBSTR (amount, LENGTH (amount) - 2,3), 'J'), 'Jsp' ); amount := SUBSTR (amount, 1, LENGTH (amount) - 3); FOR i in 1 .. v_str.COUNT LOOP EXIT WHEN (amount IS NULL); v_word := TO_CHAR (TO_DATE (SUBSTR (amount, LENGTH (amount) - 1,2), 'J'), 'Jsp' ) || v_str (i) || v_word; amount := SUBSTR (amount, 1, LENGTH (amount) - 2); END LOOP;

END IF;

v_word := v_word || ' ' || v_word1 || ' only '; v_word := REPLACE (RTRIM (v_word), ' ', ' '); v_word := REPLACE (RTRIM (v_word), '-', ' ');

RETURN INITCAP (v_word);END;

Index

24. Function for displaying Numbers in Words:SELECT TO_CHAR( TO_DATE( SUBSTR( TO_CHAR(5373484),1),'j'),'Jsp') FROM DUAL;

Only up to integers from 1 to 5373484

Index

25. Query for deleting alternate even rows FROM a table :

DELETEFROM srinuWHERE (ROWID,0) IN (SELECT ROWID, MOD(ROWNUM,2) FROM srinu);

Index

26. Query for deleting alternate odd rows FROM a table :

DELETEFROM srinuWHERE (ROWID,1) IN (SELECT ROWID, MOD(ROWNUM,2) FROM srinu);

Index

27. Procedure for sending Email :

CREATE OR REPLACE PROCEDURE Send_Mail IS sender VARCHAR2(50) := 'sender@something.com'; recipient VARCHAR2(50) := 'recipient@something.com'; subject VARCHAR2(100) := 'Test Message';message VARCHAR2(1000) := 'This is a sample mail ....';lv_mailhost VARCHAR2(30) := 'HOTNT002'; l_mail_conn utl_smtp.connection; lv_crlf VARCHAR2(2):= CHR( 13 ) || CHR( 10 ); BEGIN l_mail_conn := utl_smtp.open_connection (lv_mailhost, 80); utl_smtp.helo ( l_mail_conn, lv_mailhost); utl_smtp.mail ( l_mail_conn, sender); utl_smtp.rcpt ( l_mail_conn, recipient); utl_smtp.open_data (l_mail_conn); utl_smtp.write_data ( l_mail_conn, 'FROM: ' || sender || lv_crlf); utl_smtp.write_data ( l_mail_conn, 'To: ' || recipient || lv_crlf); utl_smtp.write_data ( l_mail_conn, 'Subject:' || subject || lv_crlf); utl_smtp.write_data ( l_mail_conn, lv_crlf || message); utl_smtp.close_data(l_mail_conn); utl_smtp.quit(l_mail_conn);

EXCEPTION WHEN OTHERS THEN

DBMS_OUTPUT.PUT_LINE('Error');END; /

Index

28. Alternate Query for DECODE function :

SELECT case WHEN sex = 'm' THEN 'male'WHEN sex = 'f' THEN 'female'ELSE 'unknown'END

FROM mytable;

Index

29. Create table adding Constraint to a date field to SYSDATE or 3 months later:

CREATE TABLE srinu(dt1 date DEFAULT SYSDATE, dt2 date,CONSTRAINT check_dt2 CHECK ((dt2 >= dt1) AND (dt2 <= ADD_MONTHS(SYSDATE,3)));

Index

30. Query to list all the suppliers who supply all the parts supplied by supplier 'S2' :

SELECT DISTINCT a.SUPPFROM ORDERS aWHERE a.supp != 'S2'AND a.parts IN(SELECT DISTINCT PARTS FROM ORDERS WHERE supp = 'S2')GROUP BY a.SUPPHAVINGCOUNT(DISTINCT a.PARTS) >=(SELECT COUNT(DISTINCT PARTS) FROM ORDERS WHERE supp = 'S2');

Table : orders

SUPP PARTS-------------------- -------S1 P1S1 P2S1 P3S1 P4S1 P5S1 P6S2 P1S2 P2S3 P2S4 P2S4 P4S4 P5

Index

31. Query to get the last Sunday of any month :

SELECT NEXT_DAY(LAST_DAY(TO_DATE('26-10-2001','DD-MM-YYYY')) - 7,'sunday') FROM DUAL;

Index

32. Query to get all those who have no children themselves :

table data :id name parent_id-------------------------------1 a NULL - the top level entry2 b 1 - a child of 13 c 14 d 2 - a child of 25 e 2 6 f 37 g 38 h 49 i 810 j 9

SELECT ID FROM MY_TABlE

WHERE PARENT_ID IS NOT NULLMINUSSELECT PARENT_ID FROM MY_TABlE;

Index

33. Query to SELECT last N rows FROM a table :

SELECT empno FROM emp WHERE ROWID in(SELECT ROWID FROM empMINUSSELECT ROWID FROM emp WHERE ROWNUM <= (SELECT COUNT(*)-5 FROM emp));

Index

34. SELECT with variables:

CREATE OR REPLACE PROCEDURE dispASxTableName varchar2(25):='emp';xFieldName varchar2(25):='ename';xValue NUMBER;xQuery varchar2(100);name varchar2(10) := 'CLARK';BEGINxQuery := 'SELECT SAL FROM ' || xTableName || ' WHERE ' || xFieldName ||

' = ''' || name || '''';

DBMS_OUTPUT.PUT_LINE(xQuery);

EXECUTE IMMEDIATE xQuery INTO xValue;DBMS_OUTPUT.PUT_LINE(xValue);END;

Index

35. Query to get the DB Name:

SELECT name FROM v$database;

Index

36. Getting the current default schema :

SELECT SYS_CONTEXT('USERENV','CURRENT_SCHEMA') FROM DUAL;

Index

37. Query to get all the column names of a particular table :

SELECT column_nameFROM all_tab_columnsWHERE TABLE_NAME = 'ORDERS';

Index

38. How do I spool only the query result to a file in SQLPLUS :

Place the following lines of code in a file and execute the file in SQLPLUS :

set heading offset feedback offset colsep ' 'set termout offset verify offspool c:\srini.txtSELECT empno,ename FROM emp; /* Write your Query here */spool off/

Index

39. Query for getting the current SessionID :

SELECT SYS_CONTEXT('USERENV','SESSIONID') Session_ID FROM DUAL;

Index

40. Query to display rows FROM m to n :

To display rows 5 to 7 :

SELECT DEPTNO, ENAME, SALFROM EMPWHERE ROWID IN

(SELECT ROWID FROM EMP WHERE ROWNUM <= 7 MINUSSELECT ROWID FROM EMPWHERE ROWNUM < 5);

OR

SELECT ename FROM empGROUP BY ROWNUM, enameHAVING ROWNUM > 1 and ROWNUM < 3;

Index

41. Query to count no. Of columns in a table:

SELECT COUNT(column_name) FROM user_tab_columns WHERE table_name = 'MYTABLE';

Index

42. Procedure to increase the buffer length :

dbms_output.enable(4000); /*allows the output buffer to be increased to the specified number of bytes */

DECLAREBEGINdbms_output.enable(4000);FOR i IN 1..400LOOPDBMS_OUTPUT.PUT_LINE(i);END LOOP;END;/

Index

43. Inserting an & symbol in a Varchar2 column :

Set the following to some other character. By default it is &.

set define '~'

Index

44. How do you remove Trailing blanks in a spooled file :Change the Environment Options Like this :set trimspool onset trimout on

Index

45. Samples for executing Dynamic SQL Statements :

Sample :1CREATE OR REPLACE PROCEDURE CNT(P_TABLE_NAME IN VARCHAR2)ASSqlString VARCHAR2(200);tot number;BEGINSqlString:='SELECT COUNT(*) FROM '|| P_TABLE_NAME;EXECUTE IMMEDIATE SqlString INTO tot;DBMS_OUTPUT.PUT_LINE('Total No.Of Records In ' || P_TABLE_NAME || ' ARE=' || tot);END;

Sample :2DECLARE

sql_stmt VARCHAR2(200);plsql_block VARCHAR2(500);emp_id NUMBER(4) := 7566;salary NUMBER(7,2);dept_id NUMBER(2) := 50;dept_name VARCHAR2(14) := ’PERSONNEL’;location VARCHAR2(13) := ’DALLAS’;

emp_rec emp%ROWTYPE;BEGIN

EXECUTE IMMEDIATE 'CREATE TABLE bonus (id NUMBER, amt NUMBER)';

sql_stmt := 'INSERT INTO dept VALUES (:1, :2, :3)';EXECUTE IMMEDIATE sql_stmt USING dept_id, dept_name, location;

sql_stmt := 'SELECT * FROM emp WHERE empno = :id';EXECUTE IMMEDIATE sql_stmt INTO emp_rec USING emp_id;

plsql_block := 'BEGIN emp_pkg.raise_salary(:id, :amt); END;';EXECUTE IMMEDIATE plsql_block USING 7788, 500;

sql_stmt := 'UPDATE emp SET sal = 2000 WHERE empno = :1RETURNING sal INTO :2';EXECUTE IMMEDIATE sql_stmt USING emp_id RETURNING INTO salary;

EXECUTE IMMEDIATE 'DELETE FROM dept WHERE deptno = :num'USING dept_id;

EXECUTE IMMEDIATE ’ALTER SESSION SET SQL_TRACE TRUE’;END;

Sample 3CREATE OR REPLACE PROCEDURE DEPARTMENTS(NO IN DEPT.DEPTNO%TYPE) AS

v_cursor integer; v_dname char(20); v_rows integer;BEGIN v_cursor := DBMS_SQL.OPEN_CURSOR; DBMS_SQL.PARSE(v_cursor, 'select dname from dept where deptno > :x',

DBMS_SQL.V7); DBMS_SQL.BIND_VARIABLE(v_cursor, ':x', no); DBMS_SQL.DEFINE_COLUMN_CHAR(v_cursor, 1, v_dname, 20); v_rows := DBMS_SQL.EXECUTE(v_cursor); LOOP IF DBMS_SQL.FETCH_ROWS(v_cursor) = 0 THEN EXIT; END IF; DBMS_SQL.COLUMN_VALUE_CHAR(v_cursor, 1, v_dname); DBMS_OUTPUT.PUT_LINE('Deptartment name: '||v_dname); END LOOP; DBMS_SQL.CLOSE_CURSOR(v_cursor);EXCEPTION WHEN OTHERS THEN DBMS_SQL.CLOSE_CURSOR(v_cursor); raise_application_error(-20000, 'Unknown Exception Raised: '||sqlcode||' '||

sqlerrm);END;

Index

46.Differences between SQL and MS-Access :

Difference 1:Oracle : select name from table1 where name like 'k%';Access: select name from table1 where name like 'k*';

Difference 2:Access: SELECT TOP 2 name FROM Table1;Oracle : will not work there is no such TOP key word.

Index

47. Query to display all the children, sub children of a parent :

SELECT organization_id,nameFROM hr_all_organization_unitsWHERE organization_id in(SELECT ORGANIZATION_ID_CHILD FROM PER_ORG_STRUCTURE_ELEMENTSCONNECT BY PRIORORGANIZATION_ID_CHILD = ORGANIZATION_ID_PARENTSTART WITH ORGANIZATION_ID_CHILD = (SELECT organization_idFROM hr_all_organization_unitsWHERE name = 'EBG Corporate Group'));

Index

48. Procedure to read/write data from a text file :

CREATE OR REPLACE PROCEDURE read_dataASc_path varchar2(100) := '/usr/tmp';c_file_name varchar2(20) := 'EKGSEP01.CSV';v_file_id utl_file.file_type;v_buffer varchar2(1022) := This is a sample text’;BEGINv_file_id := UTL_FILE.FOPEN(c_path,c_file_name,'w');UTL_FILE.PUT_LINE(v_file_id, v_buffer);UTL_FILE.FCLOSE(v_file_id);

v_file_id := UTL_FILE.FOPEN(c_path,c_file_name,'r');UTL_FILE.GET_LINE(v_file_id, v_buffer);DBMS_OUTPUT.PUT_LINE(v_buffer);UTL_FILE.FCLOSE(v_file_id);END;/

Index

49. Query to display random number between any two given numbers :

SELECT DBMS_RANDOM.VALUE (1,2) FROM DUAL;

Index

50. How can I get the time difference between two date columns :

SELECT FLOOR((date1-date2)*24*60*60)/3600) || ' HOURS ' || FLOOR((((date1-date2)*24*60*60) - FLOOR(((date1-date2)*24*60*60)/3600)*3600)/60) || ' MINUTES ' || ROUND((((date1-date2)*24*60*60) - FLOOR(((date1-date2)*24*60*60)/3600)*3600 - (FLOOR((((date1-date2)*24*60*60) - FLOOR(((date1-date2)*24*60*60)/3600)*3600)/60)*60))) || ' SECS ' time_differenceFROM my_table;

Index

51. Using INSTR and SUBSTR

I have this string in a column named location

LOT 8 CONC3 RR

Using instr and substr, I want to take whatever value follows LOT and putit into a different column and whatever value follows CONC and put it intoa different column

select substr('LOT 8 CONC3 RR',4,instr('LOT 8 CONC3 RR','CONC')-4) fromdual;

select substr('LOT 8 CONC3 RR',-(length('LOT 8 CONC3 RR')-(instr('LOT 8CONC3 RR','CONC')+3))) from dual

Index

52. View procedure code

select text from all_source where name = 'X'order by line;select text from user_source where name = 'X'select text from user_source where type = 'procedure' andname='procedure_name';select name,text from dba_source where name='ur_procedure'and owner='scott';

Index

53. To convert signed number to number in oracle

select to_number('-999,999.99', 's999,999.99') from dual; -999,999.99select to_number('+0,123.45', 's999,999,999.99') from dual; 123.45select to_number('+999,999.99', 's999,999.99') from dual; 999,999.99

Index

54. Columns of a table

select column_name from user_tab_columns where TABLE_NAME = 'EMP'select column_name from all_tab_columns where TABLE_NAME = 'EMP'select column_name from dba_tab_columns where TABLE_NAME = 'EMP'select column_name from cols where TABLE_NAME = 'EMP'

Index

55. Delete rows conditionallyI have a table have a,b,c field,

a,b should be unique, and leave max(c) row in.How can I delete other rows?

delete from 'table'where (a,b,c) not in (select a,b,max(c) from 'table' group by a,b);

Index

56.CLOB to Char

1) This function helps if your clob column value not exceed 4000 bytes(varchar2 limit).if clob column's data exceeds 4000 limit, you have tofollow different approach.

create or replace function lob_to_char(clob_col clob) return varchar2 IS buffer varchar2(4000); amt BINARY_INTEGER := 4000; pos INTEGER := 1; l clob; bfils bfile; l_var varchar2(4000):=''; begin LOOP

if dbms_lob.getlength(clob_col)<=4000 THEN dbms_lob.read (clob_col, amt, pos, buffer); l_var := l_var||buffer; pos:=pos+amt;

ELSE l_var:= 'Cannot convert to varchar2..Exceeding varchar2 field

limit'; exit;

END IF; END LOOP; return l_var; EXCEPTION

WHEN NO_DATA_FOUND THEN return l_var; END;

2) CREATE GLOBAL TEMPORARY TABLE temp_tab(id number,varchar_colvarchar2(4000));

SQL> var r refcursorSQL> exec lobpkg.lob_to_char(:r);SQL> print r

create or replace package lobpkg istype ref1 is ref cursor;n number:=0;PROCEDURE lob_to_char(rvar IN OUT lobpkg.ref1) ;end;/

create or replace package body lobpkg is

PROCEDURE lob_to_char(rvar IN OUT lobpkg.ref1) ISbuffer varchar2(4000);amt BINARY_INTEGER := 4000;pos INTEGER := 1;l clob;r lobpkg.ref1;bfils bfile;l_var varchar2(4000):='';CURSOR C1 IS SELECT * FROM clob_tab;-- change clob_tab to your_table_namebeginn:=n+1;FOR crec IN c1 LOOPamt:=4000;pos:=1;BEGIN

LOOP

--change crec.clob_col to crec.your_column_name

dbms_lob.read (crec.clob_col, amt, pos, buffer);

--change next line if you create temporary table with different name

insert into temp_tab values (n,buffer);

pos:=pos+amt;

END LOOP;EXCEPTION

WHEN NO_DATA_FOUND THENNULL;

END;END LOOP;--change next line if you create temporary table with different nameopen rvar for select vchar from temp_tab where id=n;

END;END;

Index

57. Change Settings

Open file oracle_home\plus32\glogin.sql andadd this set linesize 100set pagewidth 20and save the fileand exit from sql and reload then it will set it.

Index

58. Double quoting a Single quoted String

declare -- we need one here to get a single quote into the variable v_str varchar2 (20) := 'O''reilly''s'; begin DBMS_OUTPUT.PUT_LINE ( 'original single quoted v_str= ' || v_str ); v_str := replace(v_str, '''', ''''''); DBMS_OUTPUT.PUT_LINE ( 'after double quoted v_str= ' || v_str ); end;SQL> /original single quoted v_str= O'reilly'safter double quoted v_str= O''reilly''s

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59. Time Conversion

CREATE OR REPLACE FUNCTION to_hms (i_days IN number) RETURN varchar2ISBEGIN RETURN TO_CHAR (TRUNC (i_days)) &#124&#124 ' days ' &#124&#124

TO_CHAR (TRUNC (SYSDATE) + MOD (i_days, 1), 'HH24:MI:SS');END to_hms;

select to_hms(to_date('17-Jan-2002 13:20:20', 'dd-Mon-yyyy hh24:mi:ss') - to_date('11-Jan-2002 11:05:05', 'dd-Mon-yyyy hh24:mi:ss')) fromdual;

Index

60. Table comparisonThe table in both the schemas should have exactly the same structure. The data init could be same or different a-b and b-a

select * from a.a minus select * from b.a and select * from b.a minus select * from a.a

Index

61.Running Jobs

select * from user_jobs;exec dbms_job.remove(job_no);

Index

62.Switching ColumnsUpdate tblname Set column1 = column2,

Column2 = column1;

Index

63.Replace and RoundI have the number e.g. 63,9823874012983 and I want to round it to 63,98 and at the

same time change the , to a .

select round(replace('63,9823874012983',',','.'),2) from dual;

Index

64.First date of the yearselect trunc(sysdate, 'y') from dual;

01-jan-2002

last year this month through a select statementselect add_months(sysdate, -12) from dual;05-APR-01

Index

65.Create Sequencecreate sequence sh increment by 1 start with 0;

Index

66.Cursorscursor is someting like pointers in C language.u fetch the data using cursor.( wiz...store it somewhere temporarily). ucan do any manipulation to the data that is fetched by the cursor. liketrim, padd, concat or validate. all this are done in temporary areas calledas context area or the cursor area. u can insert this data again in someother table or do anything u want!!...like setting up some flags etc.U can display the contents of cursor using the dbms_output only. U cancreate an anonymous plsql block or a stored procedure. the major advantage

of cursors is that you can fetch more thatn one row and u can loop throughthe resultset and do the manupulations in a secure manner.

set serveroutput on;declarecursor c1 is select * from emp;beginfor var in c1 loopexit when c1%notfound;dbms_output.put_line('the employee' &#124&#124 var.ename &#124&#124'draws asalary of '&#124&#124 var.sal);end loop;end;

Index

67.Current Week

select next_day(sysdate-7,'SUNDAY'), next_day(sysdate,'SATURDAY') from dual;

NEXT_DAY( NEXT_DAY(--------- ---------07-APR-02 13-APR-02

Index

Interview Questions for Oracle, DBA, Developer Candidates

PL/SQL Questions:

1. Describe the difference between a procedure, function and anonymous pl/sql block.Level: LowExpected answer : Candidate should mention use of DECLARE statement, a function must return a value while a procedure doesn’t have to.

2. What is a mutating table error and how can you get around it?Level: IntermediateExpected answer: This happens with triggers. It occurs because the trigger is trying to update a row it is currently using. The usual fix involves either use of views or temporary tables so the database is selecting from one while updating the other.

3. Describe the use of %ROWTYPE and %TYPE in PL/SQL Level: LowExpected answer: %ROWTYPE allows you to associate a variable with an entire table row. The %TYPE associates a variable with a single column type.

4. What packages (if any) has Oracle provided for use by developers?Level: Intermediate to high

Expected answer: Oracle provides the DBMS_ series of packages. There are many which developers should be aware of such as DBMS_SQL, DBMS_PIPE, DBMS_TRANSACTION, DBMS_LOCK, DBMS_ALERT, DBMS_OUTPUT, DBMS_JOB, DBMS_UTILITY, DBMS_DDL, UTL_FILE. If they can mention a few of these and describe how they used them, even better. If they include the SQL routines provided by Oracle, great, but not really what was asked.

5. Describe the use of PL/SQL tablesLevel: IntermediateExpected answer: PL/SQL tables are scalar arrays that can be referenced by a binary integer. They can be used to hold values for use in later queries or calculations. In Oracle 8 they will be able to be of the %ROWTYPE designation, or RECORD.

6. When is a declare statement needed?Level: LowThe DECLARE statement is used in PL/SQL anonymous blocks such as with stand alone, non-stored PL/SQL procedures. It must come first in a PL/SQL stand alone file if it is used.

7. In what order should a open/fetch/loop set of commands in a PL/SQL block be implemented if you use the %NOTFOUND cursor variable in the exit when statement? Why?Level: IntermediateExpected answer: OPEN then FETCH then LOOP followed by the exit when. If not specified in this order will result in the final return being done twice because of the way the %NOTFOUND is handled by PL/SQL.

8. What are SQLCODE and SQLERRM and why are they important for PL/SQL developers?Level: IntermediateExpected answer: SQLCODE returns the value of the error number for the last error encountered. The SQLERRM returns the actual error message for the last error encountered. They can be used in exception handling to report, or, store in an error log table, the error that occurred in the code. These are especially useful for the WHEN OTHERS exception.

9. How can you find within a PL/SQL block, if a cursor is open?Level: LowExpected answer: Use the %ISOPEN cursor status variable.

10. How can you generate debugging output from PL/SQL?Level:Intermediate to highExpected answer: Use the DBMS_OUTPUT package. Another possible method is to just use the SHOW ERROR command, but this only shows errors. The DBMS_OUTPUT package can be used to show intermediate results from loops and the

status of variables as the procedure is executed. The new package UTL_FILE can also be used.

11. What are the types of triggers?Level:Intermediate to highExpected answer: There are 12 types of triggers in PL/SQL that consist of combinations of the BEFORE, AFTER, ROW, TABLE, INSERT, UPDATE, DELETE and ALL key words:BEFORE ALL ROW INSERTAFTER ALL ROW INSERTBEFORE INSERTAFTER INSERT etc.

DBA1. Give one method for transferring a table from one schema to another:Level:IntermediateExpected answer:There are several possible methods, export-import, CREATE TABLE... AS SELECT, or COPY.

2. What is the purpose of the IMPORT option IGNORE? What is it’s default setting?Level: LowExpected answer: The IMPORT IGNORE option tells import to ignore "already exists" errors. If it is not specified the tables that already exist will be skipped. If it is specified, the error is ignored and the tables data will be inserted. The default value is N.

3. You have a rollback segment in a version 7.2 database that has expanded beyond optimal, how can it be restored to optimal?Level: LowExpected answer: Use the ALTER TABLESPACE ..... SHRINK command.

4. If the DEFAULT and TEMPORARY tablespace clauses are left out of a CREATE USER command what happens? Is this bad or good? Why?Level: LowExpected answer:The user is assigned the SYSTEM tablespace as a default and temporary tablespace. This is bad because it causes user objects and temporary segments to be placed into the SYSTEM tablespace resulting in fragmentation and improper table placement (only data dictionary objects and the system rollback segment should be in SYSTEM).

5. What are some of the Oracle provided packages that DBAs should be aware of?Level: Intermediate to HighExpected answer: Oracle provides a number of packages in the form of the DBMS_ packages owned by the SYS user. The packages used by DBAs may include: DBMS_SHARED_POOL, DBMS_UTILITY, DBMS_SQL, DBMS_DDL,

DBMS_SESSION, DBMS_OUTPUT and DBMS_SNAPSHOT. They may also try to answer with the UTL*.SQL or CAT*.SQL series of SQL procedures. These can be viewed as extra credit but aren’t part of the answer.

6. What happens if the constraint name is left out of a constraint clause?Level: LowExpected answer:The Oracle system will use the default name of SYS_Cxxxx where xxxx is a system generated number. This is bad since it makes tracking which table the constraint belongs to or what the constraint does harder.

7. What happens if a tablespace clause is left off of a primary key constraint clause?Level: LowExpected answer: This results in the index that is automatically generated being placed in then users default tablespace. Since this will usually be the same tablespace as the table is being created in, this can cause serious performance problems.

8. What is the proper method for disabling and re-enabling a primary key constraint?Level: IntermediateExpected answer: You use the ALTER TABLE command for both. However, for the enable clause you must specify the USING INDEX and TABLESPACE clause for primary keys.

9. What happens if a primary key constraint is disabled and then enabled without fully specifying the index clause?Level: IntermediateExpected answer: The index is created in the user’s default tablespace and all sizing information is lost. Oracle doesn’t store this information as a part of the constraint definition, but only as part of the index definition, when the constraint was disabled the index was dropped and the information is gone.

10. (On UNIX) When should more than one DB writer process be used? How many should be used?Level: HighExpected answer:If the UNIX system being used is capable of asynchronous IO then only one is required, if the system is not capable of asynchronous IO then up to twice the number of disks used by Oracle number of DB writers should be specified by use of the db_writers initialization parameter.

11. You are using hot backup without being in archivelog mode, can you recover in the event of a failure? Why or why not?Level: HighExpected answer:You can’t use hot backup without being in archivelog mode. So no, you couldn’t recover.

12. What causes the "snapshot too old" error? How can this be prevented or mitigated?

Level: IntermediateExpected answer: This is caused by large or long running transactions that have either wrapped onto their own rollback space or have had another transaction write on part of their rollback space. This can be prevented or mitigated by breaking the transaction into a set of smaller transactions or increasing the size of the rollback segments and their extents.

13. How can you tell if a database object is invalid?Level: LowExpected answer: By checking the status column of the DBA_, ALL_ or USER_OBJECTS views, depending upon whether you own or only have permission on the view or are using a DBA account.

14. A user is getting an ORA-00942 error yet you know you have granted them permission on the table, what else should you check?Level: LowExpected answer: You need to check that the user has specified the full name of the object (select empid from scott.emp; instead of select empid from emp;) or has a synonym that points to the object (create synonym emp for scott.emp;)

15. A developer is trying to create a view and the database won’t let him. He has the "DEVELOPER" role which has the "CREATE VIEW" system privilege and SELECT grants on the tables he is using, what is the problem?Level: IntermediateExpected answer: You need to verify the developer has direct grants on all tables used in the view. You can’t create a stored object with grants given through views.

16. If you have an example table, what is the best way to get sizing data for the production table implementation?Level: IntermediateExpected answer: The best way is to analyze the table and then use the data provided in the DBA_TABLES view to get the average row length and other pertinent data for the calculation. The quick and dirty way is to look at the number of blocks the table is actually using and ratio the number of rows in the table to its number of blocks against the number of expected rows.

17. How can you find out how many users are currently logged into the database? How can you find their operating system id?Level: highExpected answer: There are several ways. One is to look at the v$session or v$process views. Another way is to check the current_logins parameter in the v$sysstat view. Another if you are on UNIX is to do a "ps -ef|grep oracle|wc -l’ command, but this only works against a single instance installation.

18. A user selects from a sequence and gets back two values, his select is:SELECT pk_seq.nextval FROM dual;

What is the problem?Level: IntermediateExpected answer: Somehow two values have been inserted into the dual table. This table is a single row, single column table that should only have one value in it.

19. How can you determine if an index needs to be dropped and rebuilt?Level: IntermediateExpected answer: Run the ANALYZE INDEX command on the index to validate its structure and then calculate the ratio of LF_BLK_LEN/LF_BLK_LEN+BR_BLK_LEN and if it isn’t near 1.0 (i.e. greater than 0.7 or so) then the index should be rebuilt. Or if the ratio BR_BLK_LEN/ LF_BLK_LEN+BR_BLK_LEN is nearing 0.3.

SQL/ SQLPlus

1. How can variables be passed to a SQL routine?Level: LowExpected answer: By use of the & symbol. For passing in variables the numbers 1-8 can be used (&1, &2,...,&8) to pass the values after the command into the SQLPLUS session. To be prompted for a specific variable, place the ampersanded variable in the code itself:"select * from dba_tables where owner=&owner_name;" . Use of double ampersands tells SQLPLUS to resubstitute the value for each subsequent use of the variable, a single ampersand will cause a reprompt for the value unless an ACCEPT statement is used to get the value from the user.

2. You want to include a carriage return/linefeed in your output from a SQL script, how can you do this?Level: Intermediate to highExpected answer: The best method is to use the CHR() function (CHR(10) is a return/linefeed) and the concatenation function "||". Another method, although it is hard to document and isn’t always portable is to use the return/linefeed as a part of a quoted string.

3. How can you call a PL/SQL procedure from SQL?Level: IntermediateExpected answer: By use of the EXECUTE (short form EXEC) command.

4. How do you execute a host operating system command from within SQL?Level: LowExpected answer: By use of the exclamation point "!" (in UNIX and some other OS) or the HOST (HO) command.

5. You want to use SQL to build SQL, what is this called and give an exampleLevel: Intermediate to highExpected answer: This is called dynamic SQL. An example would be:

set lines 90 pages 0 termout off feedback off verify offspool drop_all.sqlselect ‘drop user ‘||username||’ cascade;’ from dba_userswhere username not in ("SYS’,’SYSTEM’);spool offEssentially you are looking to see that they know to include a command (in this case DROP USER...CASCADE;) and that you need to concatenate using the ‘||’ the values selected from the database.

6. What SQLPlus command is used to format output from a select?Level: lowExpected answer: This is best done with the COLUMN command.

7. You want to group the following set of select returns, what can you group on?Max(sum_of_cost), min(sum_of_cost), count(item_no), item_noLevel: IntermediateExpected answer:The only column that can be grouped on is the "item_no" column, the rest have aggregate functions associated with them.

8. What special Oracle feature allows you to specify how the cost based system treats a SQL statement?Level: Intermediate to highExpected answer: The COST based system allows the use of HINTs to control the optimizer path selection. If they can give some example hints such as FIRST ROWS, ALL ROWS, USING INDEX, STAR, even better.

9. You want to determine the location of identical rows in a table before attempting to place a unique index on the table, how can this be done?Level: HighExpected answer: Oracle tables always have one guaranteed unique column, the rowid column. If you use a min/max function against your rowid and then select against the proposed primary key you can squeeze out the rowids of the duplicate rows pretty quick. For example:select rowid from emp ewhere e.rowid > (select min(x.rowid)from emp xwhere x.emp_no = e.emp_no);In the situation where multiple columns make up the proposed key, they must all be used in the where clause. 10. What is a Cartesian product?Level: LowExpected answer: A Cartesian product is the result of an unrestricted join of two or more tables. The result set of a three table Cartesian product will have x * y * z number of rows where x, y, z correspond to the number of rows in each table involved in the join.

11. You are joining a local and a remote table, the network manager complains about the traffic involved, how can you reduce the network traffic?Level: HighExpected answer:Push the processing of the remote data to the remote instance by using a view to pre-select the information for the join. This will result in only the data required for the join being sent across.12. What is the default ordering of an ORDER BY clause in a SELECT statement?Level: LowExpected answer: Ascending

13. What is tkprof and how is it used?Level: Intermediate to highExpected answer: The tkprof tool is a tuning tool used to determine cpu and execution times for SQL statements. You use it by first setting timed_statistics to true in the initialization file and then turning on tracing for either the entire database via the sql_trace parameter or for the session using the ALTER SESSION command. Once the trace file is generated you run the tkprof tool against the trace file and then look at the output from the tkprof tool. This can also be used to generate explain plan output.

14. What is explain plan and how is it used?Level: Intermediate to highExpected answer: The EXPLAIN PLAN command is a tool to tune SQL statements. To use it you must have an explain_table generated in the user you are running the explain plan for. This is created using the utlxplan.sql script. Once the explain plan table exists you run the explain plan command giving as its argument the SQL statement to be explained. The explain_plan table is then queried to see the execution plan of the statement. Explain plans can also be run using tkprof.

15. How do you set the number of lines on a page of output? The width?Level: LowExpected answer: The SET command in SQLPLUS is used to control the number of lines generated per page and the width of those lines, for example SET PAGESIZE 60 LINESIZE 80 will generate reports that are 60 lines long with a line width of 80 characters. The PAGESIZE and LINESIZE options can be shortened to PAGES and LINES.

16. How do you prevent output from coming to the screen?Level: LowExpected answer: The SET option TERMOUT controls output to the screen. Setting TERMOUT OFF turns off screen output. This option can be shortened to TERM.

17. How do you prevent Oracle from giving you informational messages during and after a SQL statement execution?Level: LowExpected answer: The SET options FEEDBACK and VERIFY can be set to OFF.

18. How do you generate file output from SQL?Level: LowExpected answer: By use of the SPOOL command

Tuning Questions:1. A tablespace has a table with 30 extents in it. Is this bad? Why or why not.Level: IntermediateExpected answer: Multiple extents in and of themselves aren’t bad. However if you also have chained rows this can hurt performance.

2. How do you set up tablespaces during an Oracle installation?Level: LowExpected answer: You should always attempt to use the Oracle Flexible Architecture standard or another partitioning scheme to ensure proper separation of SYSTEM, ROLLBACK, REDO LOG, DATA, TEMPORARY and INDEX segments.

3. You see multiple fragments in the SYSTEM tablespace, what should you check first?Level: LowExpected answer: Ensure that users don’t have the SYSTEM tablespace as their TEMPORARY or DEFAULT tablespace assignment by checking the DBA_USERS view.

4. What are some indications that you need to increase the SHARED_POOL_SIZE parameter?Level: IntermediateExpected answer: Poor data dictionary or library cache hit ratios, getting error ORA-04031. Another indication is steadily decreasing performance with all other tuning parameters the same.

5. What is the general guideline for sizing db_block_size and db_multi_block_read for an application that does many full table scans?Level: HighExpected answer: Oracle almost always reads in 64k chunks. The two should have a product equal to 64 or a multiple of 64.

6. What is the fastest query method for a table?Level: IntermediateExpected answer: Fetch by rowid

7. Explain the use of TKPROF? What initialization parameter should be turned on to get full TKPROF output?Level: HighExpected answer: The tkprof tool is a tuning tool used to determine cpu and execution times for SQL statements. You use it by first setting timed_statistics to true in the initialization file and then turning on tracing for either the entire database via the sql_trace parameter or for the session using the ALTER SESSION command. Once the

trace file is generated you run the tkprof tool against the trace file and then look at the output from the tkprof tool. This can also be used to generate explain plan output.

8. When looking at v$sysstat you see that sorts (disk) is high. Is this bad or good? If bad -How do you correct it?Level: IntermediateExpected answer: If you get excessive disk sorts this is bad. This indicates you need to tune the sort area parameters in the initialization files. The major sort are parameter is the SORT_AREA_SIZe parameter.

9. When should you increase copy latches? What parameters control copy latches?Level: highExpected answer: When you get excessive contention for the copy latches as shown by the "redo copy" latch hit ratio. You can increase copy latches via the initialization parameter LOG_SIMULTANEOUS_COPIES to twice the number of CPUs on your system.

10. Where can you get a list of all initialization parameters for your instance? How about an indication if they are default settings or have been changed?Level: LowExpected answer: You can look in the init<sid>.ora file for an indication of manually set parameters. For all parameters, their value and whether or not the current value is the default value, look in the v$parameter view.

11. Describe hit ratio as it pertains to the database buffers. What is the difference between instantaneous and cumulative hit ratio and which should be used for tuning?Level: IntermediateExpected answer: The hit ratio is a measure of how many times the database was able to read a value from the buffers verses how many times it had to re-read a data value from the disks. A value greater than 80-90% is good, less could indicate problems. If you simply take the ratio of existing parameters this will be a cumulative value since the database started. If you do a comparison between pairs of readings based on some arbitrary time span, this is the instantaneous ratio for that time span. Generally speaking an instantaneous reading gives more valuable data since it will tell you what your instance is doing for the time it was generated over.

12. Discuss row chaining, how does it happen? How can you reduce it? How do you correct it?Level: highExpected answer: Row chaining occurs when a VARCHAR2 value is updated and the length of the new value is longer than the old value and won’t fit in the remaining block space. This results in the row chaining to another block. It can be reduced by setting the storage parameters on the table to appropriate values. It can be corrected by export and import of the effected table.

13. When looking at the estat events report you see that you are getting busy buffer waits. Is this bad? How can you find what is causing it?Level: highExpected answer: Buffer busy waits could indicate contention in redo, rollback or data blocks. You need to check the v$waitstat view to see what areas are causing the problem. The value of the "count" column tells where the problem is, the "class" column tells you with what. UNDO is rollback segments, DATA is data base buffers.

14. If you see contention for library caches how can you fix it?Level: IntermediateExpected answer: Increase the size of the shared pool.

15. If you see statistics that deal with "undo" what are they really talking about?Level: IntermediateExpected answer: Rollback segments and associated structures.

16. If a tablespace has a default pctincrease of zero what will this cause (in relationship to the smon process)?Level: HighExpected answer: The SMON process won’t automatically coalesce its free space fragments.

17. If a tablespace shows excessive fragmentation what are some methods to defragment the tablespace? (7.1,7.2 and 7.3 only)Level: HighExpected answer: In Oracle 7.0 to 7.2 The use of the 'alter session set events 'immediate trace name coalesce level ts#';’ command is the easiest way to defragment contiguous free space fragmentation. The ts# parameter corresponds to the ts# value found in the ts$ SYS table. In version 7.3 the ‘alter tablespace <name> coalesce;’ is best. If the free space isn’t contiguous then export, drop and import of the tablespace contents may be the only way to reclaim non-contiguous free space.

18. How can you tell if a tablespace has excessive fragmentation?Level: IntermediateIf a select against the dba_free_space table shows that the count of a tablespaces extents is greater than the count of its data files, then it is fragmented.

19. You see the following on a status report:redo log space requests 23redo log space wait time 0Is this something to worry about? What if redo log space wait time is high? How can you fix this?Level: IntermediateExpected answer: Since the wait time is zero, no. If the wait time was high it might indicate a need for more or larger redo logs.

20. What can cause a high value for recursive calls? How can this be fixed?Level: HighExpected answer: A high value for recursive calls is cause by improper cursor usage, excessive dynamic space management actions, and or excessive statement re-parses. You need to determine the cause and correct it By either relinking applications to hold cursors, use proper space management techniques (proper storage and sizing) or ensure repeat queries are placed in packages for proper reuse.

21. If you see a pin hit ratio of less than 0.8 in the estat library cache report is this a problem? If so, how do you fix it?Level: IntermediateExpected answer: This indicate that the shared pool may be too small. Increase the shared pool size.

22. If you see the value for reloads is high in the estat library cache report is this a matter for concern?Level: IntermediateExpected answer: Yes, you should strive for zero reloads if possible. If you see excessive reloads then increase the size of the shared pool.

23. You look at the dba_rollback_segs view and see that there is a large number of shrinks and they are of relatively small size, is this a problem? How can it be fixed if it is a problem?Level: HighExpected answer: A large number of small shrinks indicates a need to increase the size of the rollback segment extents. Ideally you should have no shrinks or a small number of large shrinks. To fix this just increase the size of the extents and adjust optimal accordingly.

24. You look at the dba_rollback_segs view and see that you have a large number of wraps is this a problem?Level: HighExpected answer: A large number of wraps indicates that your extent size for your rollback segments are probably too small. Increase the size of your extents to reduce the number of wraps. You can look at the average transaction size in the same view to get the information on transaction size.

25. In a system with an average of 40 concurrent users you get the following from a query on rollback extents:ROLLBACK CUR EXTENTS --------------------- -------------------------- R01 11 R02 8R03 12R04 9SYSTEM 4

You have room for each to grow by 20 more extents each. Is there a problem? Should you take any action?Level: IntermediateExpected answer: No there is not a problem. You have 40 extents showing and an average of 40 concurrent users. Since there is plenty of room to grow no action is needed.

26. You see multiple extents in the temporary tablespace. Is this a problem?Level: IntermediateExpected answer: As long as they are all the same size this isn’t a problem. In fact, it can even improve performance since Oracle won’t have to create a new extent when a user needs one.

Installation/Configuration1. Define OFA.Level: LowExpected answer: OFA stands for Optimal Flexible Architecture. It is a method of placing directories and files in an Oracle system so that you get the maximum flexibility for future tuning and file placement.

2. How do you set up your tablespace on installation?Level: LowExpected answer: The answer here should show an understanding of separation of redo and rollback, data and indexes and isolation os SYSTEM tables from other tables. An example would be to specify that at least 7 disks should be used for an Oracle installation so that you can place SYSTEM tablespace on one, redo logs on two (mirrored redo logs) the TEMPORARY tablespace on another, ROLLBACK tablespace on another and still have two for DATA and INDEXES. They should indicate how they will handle archive logs and exports as well. As long as they have a logical plan for combining or further separation more or less disks can be specified.

3. What should be done prior to installing Oracle (for the OS and the disks)?Level: LowExpected Answer: adjust kernel parameters or OS tuning parameters in accordance with installation guide. Be sure enough contiguous disk space is available.

4. You have installed Oracle and you are now setting up the actual instance. You have been waiting an hour for the initialization script to finish, what should you check first to determine if there is a problem?Level: Intermediate to highExpected Answer: Check to make sure that the archiver isn’t stuck. If archive logging is turned on during install a large number of logs will be created. This can fill up your archive log destination causing Oracle to stop to wait for more space.

5. When configuring SQLNET on the server what files must be set up?Level: Intermediate

Expected answer: INITIALIZATION file, TNSNAMES.ORA file, SQLNET.ORA file

6. When configuring SQLNET on the client what files need to be set up?Level: IntermediateExpected answer: SQLNET.ORA, TNSNAMES.ORA

7. What must be installed with ODBC on the client in order for it to work with Oracle?Level: IntermediateExpected answer: SQLNET and PROTOCOL (for example: TCPIP adapter) layers of the transport programs.

8. You have just started a new instance with a large SGA on a busy existing server. Performance is terrible, what should you check for?Level: IntermediateExpected answer: The first thing to check with a large SGA is that it isn’t being swapped out.

9. What OS user should be used for the first part of an Oracle installation (on UNIX)?Level: lowExpected answer: You must use root first.

10. When should the default values for Oracle initialization parameters be used as is?Level: LowExpected answer: Never

11. How many control files should you have? Where should they be located? Level: LowExpected answer: At least 2 on separate disk spindles. Be sure they say on separate disks, not just file systems.

12. How many redo logs should you have and how should they be configured for maximum recoverability?Level: IntermediateExpected answer: You should have at least three groups of two redo logs with the two logs each on a separate disk spindle (mirrored by Oracle). The redo logs should not be on raw devices on UNIX if it can be avoided.

13. You have a simple application with no "hot" tables (i.e. uniform IO and access requirements). How many disks should you have assuming standard layout for SYSTEM, USER, TEMP and ROLLBACK tablespaces?Expected answer: At least 7, see disk configuration answer above.

Data Modeler

1. Describe third normal form?

Level: LowExpected answer: Something like: In third normal form all attributes in an entity are related to the primary key and only to the primary key

2. Is the following statement true or false:"All relational databases must be in third normal form"Why or why not?Level: IntermediateExpected answer: False. While 3NF is good for logical design most databases, if they have more than just a few tables, will not perform well using full 3NF. Usually some entities will be denormalized in the logical to physical transfer process.

3. What is an ERD?Level: LowExpected answer: An ERD is an Entity-Relationship-Diagram. It is used to show the entities and relationships for a database logical model.

4. Why are recursive relationships bad? How do you resolve them?Level: Intermediate A recursive relationship (one where a table relates to itself) is bad when it is a hard relationship (i.e. neither side is a "may" both are "must") as this can result in it not being possible to put in a top or perhaps a bottom of the table (for example in the EMPLOYEE table you couldn’t put in the PRESIDENT of the company because he has no boss, or the junior janitor because he has no subordinates). These type of relationships are usually resolved by adding a small intersection entity.

5. What does a hard one-to-one relationship mean (one where the relationship on both ends is "must")?Level: Low to intermediateExpected answer: This means the two entities should probably be made into one entity.

6. How should a many-to-many relationship be handled?Level: IntermediateExpected answer: By adding an intersection entity table

7. What is an artificial (derived) primary key? When should an artificial (or derived) primary key be used?Level: IntermediateExpected answer: A derived key comes from a sequence. Usually it is used when a concatenated key becomes too cumbersome to use as a foreign key.

8. When should you consider denormalization?Level: IntermediateExpected answer: Whenever performance analysis indicates it would be beneficial to do so without compromising data integrity.

UNIX1. How can you determine the space left in a file system?Level: LowExpected answer: There are several commands to do this: du, df, or bdf

2. How can you determine the number of SQLNET users logged in to the UNIX system?Level: IntermediateExpected answer: SQLNET users will show up with a process unique name that begins with oracle<SID>, if you do a ps -ef|grep oracle<SID>|wc -l you can get a count of the number of users.

3. What command is used to type files to the screen?Level: LowExpected answer: cat, more, pg

4. What command is used to remove a file?Level: LowExpected answer: rm

5. Can you remove an open file under UNIX?Level: LowExpected answer: yes

6. How do you create a decision tree in a shell script?Level: intermediateExpected answer: depending on shell, usually a case-esac or an if-endif or fi structure

7. What is the purpose of the grep command?Level: LowExpected answer: grep is a string search command that parses the specified string from the specified file or files

8. The system has a program that always includes the word nocomp in its name, how can you determine the number of processes that are using this program?Level: intermediateExpected answer: ps -ef|grep *nocomp*|wc -l

9. What is an inode?Level: IntermediateExpected answer: an inode is a file status indicator. It is stored in both disk and memory and tracts file status. There is one inode for each file on the system.

10. The system administrator tells you that the system hasn’t been rebooted in 6 months, should he be proud of this?Level: HighExpected answer: Maybe. Some UNIX systems don’t clean up well after themselves. Inode problems and dead user processes can accumulate causing possible performance and corruption problems. Most UNIX systems should have a scheduled periodic reboot so file systems can be checked and cleaned and dead or zombie processes cleared out.

11. What is redirection and how is it used?Level: IntermediateExpected answer: redirection is the process by which input or output to or from a process is redirected to another process. This can be done using the pipe symbol "|", the greater than symbol ">" or the "tee" command. This is one of the strengths of UNIX allowing the output from one command to be redirected directly into the input of another command.

12. How can you find dead processes?Level: IntermediateExpected answer: ps -ef|grep zombie -- or -- who -d depending on the system.

13. How can you find all the processes on your system?Level: LowExpected answer: Use the ps command

14. How can you find your id on a system?Level: LowExpected answer: Use the "who am i" command.

15. What is the finger command?Level: LowExpected answer: The finger command uses data in the passwd file to give information on system users.

16. What is the easiest method to create a file on UNIX?Level: LowExpected answer: Use the touch command

17. What does >> do?Level: IntermediateExpected answer: The ">>" redirection symbol appends the output from the command specified into the file specified. The file must already have been created.

18. If you aren’t sure what command does a particular UNIX function what is the best way to determine the command?

Expected answer: The UNIX man -k <value> command will search the man pages for the value specified. Review the results from the command to find the command of interest.

Oracle Troubleshooting

1. How can you determine if an Oracle instance is up from the operating system level?Level: LowExpected answer: There are several base Oracle processes that will be running on multi-user operating systems, these will be smon, pmon, dbwr and lgwr. Any answer that has them using their operating system process showing feature to check for these is acceptable. For example, on UNIX a ps -ef|grep dbwr will show what instances are up.

2. Users from the PC clients are getting messages indicating :Level: LowORA-06114: (Cnct err, can't get err txt. See Servr Msgs & Codes Manual)What could the problem be?Expected answer: The instance name is probably incorrect in their connection string.

3. Users from the PC clients are getting the following error stack:Level: LowERROR: ORA-01034: ORACLE not availableORA-07318: smsget: open error when opening sgadef.dbf file.HP-UX Error: 2: No such file or directoryWhat is the probable cause?Expected answer: The Oracle instance is shutdown that they are trying to access, restart the instance.

4. How can you determine if the SQLNET process is running for SQLNET V1? How about V2?Level: LowExpected answer: For SQLNET V1 check for the existence of the orasrv process. You can use the command "tcpctl status" to get a full status of the V1 TCPIP server, other protocols have similar command formats. For SQLNET V2 check for the presence of the LISTENER process(s) or you can issue the command "lsnrctl status".

5. What file will give you Oracle instance status information? Where is it located?Level: LowExpected answer: The alert<SID>.ora log. It is located in the directory specified by the background_dump_dest parameter in the v$parameter table.

6. Users aren’t being allowed on the system. The following message is received:Level: IntermediateORA-00257 archiver is stuck. Connect internal only, until freedWhat is the problem?

Expected answer: The archive destination is probably full, backup the archive logs and remove them and the archiver will re-start.

7. Where would you look to find out if a redo log was corrupted assuming you are using Oracle mirrored redo logs?Level: IntermediateExpected answer: There is no message that comes to the SQLDBA or SRVMGR programs during startup in this situation, you must check the alert<SID>.log file for this information.

8. You attempt to add a datafile and get:Level: IntermediateORA-01118: cannot add anymore datafiles: limit of 40 exceededWhat is the problem and how can you fix it?Expected answer: When the database was created the db_files parameter in the initialization file was set to 40. You can shutdown and reset this to a higher value, up to the value of MAX_DATAFILES as specified at database creation. If the MAX_DATAFILES is set to low, you will have to rebuild the control file to increase it before proceeding.9. You look at your fragmentation report and see that smon hasn’t coalesced any of you tablespaces, even though you know several have large chunks of contiguous free extents. What is the problem?Level: HighExpected answer: Check the dba_tablespaces view for the value of pct_increase for the tablespaces. If pct_increase is zero, smon will not coalesce their free space.

10. Your users get the following error:Level: IntermediateORA-00055 maximum number of DML locks exceededWhat is the problem and how do you fix it?Expected answer: The number of DML Locks is set by the initialization parameter DML_LOCKS. If this value is set to low (which it is by default) you will get this error. Increase the value of DML_LOCKS. If you are sure that this is just a temporary problem, you can have them wait and then try again later and the error should clear.

11. You get a call from you backup DBA while you are on vacation. He has corrupted all of the control files while playing with the ALTER DATABASE BACKUP CONTROLFILE command. What do you do?Level: HighExpected answer: As long as all datafiles are safe and he was successful with the BACKUP controlfile command you can do the following:CONNECT INTERNALSTARTUP MOUNT(Take any read-only tablespaces offline before next step ALTER DATABASE DATAFILE .... OFFLINE;)

RECOVER DATABASE USING BACKUP CONTROLFILEALTER DATABASE OPEN RESETLOGS;(bring read-only tablespaces back online)Shutdown and backup the system, then restartIf they have a recent output file from the ALTER DATABASE BACKUP CONTROL FILE TO TRACE; command, they can use that to recover as well.If no backup of the control file is available then the following will be required:CONNECT INTERNALSTARTUP NOMOUNTCREATE CONTROL FILE .....;However, they will need to know all of the datafiles, logfiles, and settings for MAXLOGFILES, MAXLOGMEMBERS, MAXLOGHISTORY, MAXDATAFILES for the database to use the command.

Oracle Concepts and Architecture Database Structures.

1.What are the components of Physical database structure of Oracle Database?

ORACLE database is comprised of three types of files. One or more Data files, two are more redo Log files, and one or more Control files.

2.What are the components of Logical database structure of ORACLE database?

Table spaces and the Database's Schema Objects.

3. What is a Table space?

A database is divided into Logical Storage Unit called table spaces. A table space is used to grouped related logical structures together.

4. What is SYSTEM table space and when is it Created?

Every ORACLE database contains a table space named SYSTEM, which is automatically created when the database is created. The SYSTEM tableSpace always contains the data dictionary tables for the entire database.

5. Explain the relationship among Database, Table space and Data file?

Each databases logically divided into one or more tableSpaces one or more data files are explicitly created for each table space.

6. What is schema?

A schema is collection of database objects of a User.

7. What are Schema Objects?Schema objects are the logical structures that directly refer to the database's data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and Database links.

8. Can objects of the same Schema reside in different table spaces?

Yes.

9. Can a Table space hold objects from different Schemes?Yes.

10. What is Table?A table is the basic unit of data storage in an ORACLE database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.

11. What is a View?

A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)

12. Do View contain Data?

Views do not contain or store data.

13. Can a View based on another View?

Yes.

14. What are the advantages of Views?

Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.Hide data complexity.Simplify commands for the user.Store complex queries.Present the data in a different perspective from that of the base table.

15. What is a Sequence?

A sequence generates a serial list of unique numbers for numerical columns of a database's tables.

16. What is a Synonym?

A synonym is an alias for a table, view, sequence or program unit.

17. What are the types of Synonyms?

There are two types of Synonyms Private and Public.

18. What is a Private Synonyms?

A Private Synonyms can be accessed only by the owner.

19. What is a Public Synonyms?

Any user on the database can access a Public synonym.

20. What are synonyms used for?

Synonyms are used to: Mask the real name and owner of an object.

Provide public access to an objectProvide location transparency for tables, views or program units of a remote database.Simplify the SQL statements for database users.

21. What is an Index?

An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on ones or more columns of a table.

22. How is Indexes Update?

Indexes are automatically maintained and used by ORACLE. Changes to table data are automatically incorporated into all relevant indexes.

23. What are Clusters?

Clusters are groups of one or more tables physically stores together to share common columns and are often used together.

24. What is cluster Key?

The related column of the tables in a cluster is called the Cluster Key.

25. What is Index Cluster?

A Cluster with an index on the Cluster Key.

26. What is Hash Cluster?

A row is stored in a hash cluster based on the result of applying a hash function to the row's cluster key value. All rows with the same hash key value are stores together on disk.

27. When can Hash Cluster used?

Hash clusters are better choice when a table is often queried with equality queries. For such queries the specified cluster key value is hashed. The resulting hash key value points directly to the area on disk that stores the specified rows.

28. What is Database Link?

A database link is a named object that describes a "path" from one database to another.

29. What are the types of Database Links?

Private Database Link, Public Database Link & Network Database Link.

30. What is Private Database Link?

Private database link is created on behalf of a specific user. A private database link can be used only when the owner of the link specifies a global object name in a SQL statement or in the definition of the owner's views or procedures.

31. What is Public Database Link?

Public database link is created for the special user group PUBLIC. A public database link can be used when any user in the associated database specifies a global object name in a SQL statement or object definition.

32. What is Network Database link?

Network database link is created and managed by a network domain service. A network database link can be used when any user of any database in the network specifies a global object name in a SQL statement or object definition.

33. What is Data Block?

ORACLE database's data is stored in data blocks. One data block corresponds to a specific number of bytes of physical database space on disk.

34. How to define Data Block size?

A data block size is specified for each ORACLE database when the database is created. A database users and allocated free database space in ORACLE data blocks. Block size is specified in INIT.ORA file and can’t be changed latter.

35. What is Row Chaining?

In Circumstances, all of the data for a row in a table may not be able to fit in the same data block. When this occurs, the data for the row is stored in a chain of data block (one or more) reserved for that segment.

36. What is an Extent?

An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.

37. What is a Segment?

A segment is a set of extents allocated for a certain logical structure.

38. What are the different types of Segments?

Data Segment, Index Segment, Rollback Segment and Temporary Segment.

39. What is a Data Segment?

Each Non-clustered table has a data segment. All of the table's data is stored in the extents of its data segment. Each cluster has a data segment. The data of every table in the cluster is stored in the cluster's data segment.

40. What is an Index Segment?

Each Index has an Index segment that stores all of its data.

41. What is Rollback Segment?

A Database contains one or more Rollback Segments to temporarily store "undo" information.

42. What are the uses of Rollback Segment?

Rollback Segments are used:To generate read-consistent database information during database recovery to rollback uncommitted transactions for users.

43. What is a Temporary Segment?

Temporary segments are created by ORACLE when a SQL statement needs a temporary work area to complete execution. When the statement finishes execution, the temporary segment extents are released to the system for future use.

44. What is a Data File?

Every ORACLE database has one or more physical data files. A database's data files contain all the database data. The data of logical database structures such as tables and indexes is physically stored in the data files allocated for a database.

45. What are the Characteristics of Data Files?

A data file can be associated with only one database. Once created a data file can't change size.One or more data files form a logical unit of database storage called a table space.

46. What is a Redo Log?

The set of Redo Log files for a database is collectively known as the database's redo log.

47. What is the function of Redo Log?

The Primary function of the redo log is to record all changes made to data.

48. What is the use of Redo Log Information?

The Information in a redo log file is used only to recover the database from a system or media failure prevents database data from being written to a database's data files.

49. What does a Control file Contain?

A Control file records the physical structure of the database. It contains the following information.

Database NameNames and locations of a database's files and redo log files.Time stamp of database creation.

50. What is the use of Control File?

When an instance of an ORACLE database is started, its control file is used to identify the database and redo log files that must be opened for database operation to proceed. It is also used in database recovery.

51. What is a Data Dictionary?

The data dictionary of an ORACLE database is a set of tables and views that are used as a read-only reference about the database.It stores information about both the logical and physical structure of the database, the valid users of an ORACLE database, integrity constraints defined for tables in the database and space allocated for a schema object and how much of it is being used.

52. What is an Integrity Constrains?

An integrity constraint is a declarative way to define a business rule for a column of a table.

53. Can an Integrity Constraint be enforced on a table if some existing table data does not satisfy the constraint?No.

54. Describe the different type of Integrity Constraints supported by ORACLE? NOT NULL Constraint - Disallows Nulls in a table's column.UNIQUE Constraint - Disallows duplicate values in a column or set of columns.PRIMARY KEY Constraint - Disallows duplicate values and Nulls in a column or set of columns.FOREIGN KEY Constrain - Require each value in a column or set of columns match a value in a related table's UNIQUE or PRIMARY KEY.CHECK Constraint - Disallows values that do not satisfy the logical expression of the constraint.

55. What is difference between UNIQUE constraint and PRIMARY KEY constraint?A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls.

56. Describe Referential Integrity?

A rule defined on a column (or set of columns) in one table that allows the insert or update of a row only if the value for the column or set of columns (the dependent value) matches a value in a column of a related table (the referenced value). It also specifies the type of data manipulation allowed on referenced data and the action to be performed on dependent data as a result of any action on referenced data.

57. What are the Referential actions supported by FOREIGN KEY integrity constraint?

UPDATE and DELETE Restrict - A referential integrity rule that disallows the update or deletion of referenced data.

DELETE Cascade - When a referenced row is deleted all associated dependent rows are deleted.

58. What is self-referential integrity constraint?If a foreign key reference a parent key of the same table is called self-referential integrity constraint.

59. What are the Limitations of a CHECK Constraint?

The condition must be a Boolean expression evaluated using the values in the row being inserted or updated and can't contain sub queries, sequence, the SYSDATE, UID, USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.

60. What is the maximum number of CHECK constraints that can be defined on a column?No Limit.

SYSTEM ARCHITECTURE:

61. What constitute an ORACLE Instance?SGA and ORACLE background processes constitute an ORACLE instance. (or) Combination of memory structure and background process.

62. What is SGA?The System Global Area (SGA) is a shared memory region allocated by ORACLE that contains data and control information for one ORACLE instance.

63. What are the components of SGA?Database buffers, Redo Log Buffer the Shared Pool and Cursors.

64. What do Database Buffers contain?

Database buffers store the most recently used blocks of database data. It can also contain modified data that has not yet been permanently written to disk.

65. What do Redo Log Buffers contain?Redo Log Buffer stores redo entries a log of changes made to the database.

66. What is Shared Pool?Shared Pool is a portion of the SGA that contains shared memory constructs such as shared SQL areas.

67. What is Shared SQL Area?A Shared SQL area is required to process every unique SQL statement submitted to a database and contains information such as the parse tree and execution plan for the corresponding statement.

68. What is Cursor?A Cursor is a handle (a name or pointer) for the memory associated with a specific statement.

69. What is PGA?Program Global Area (PGA) is a memory buffer that contains data and control information for a server process.

70. What is User Process?A user process is created and maintained to execute the software code of an application program. It is a shadow process created automatically to facilitate communication between the user and the server process.

71. What is Server Process?Server Process handles requests from connected user process. A server process is in charge of communicating with the user process and interacting with ORACLE carry out requests of the associated user process.

72. What are the two types of Server Configurations?Dedicated Server Configuration and Multi-threaded Server Configuration.

73. What is Dedicated Server Configuration?

In a Dedicated Server Configuration a Server Process handles requests for a Single User Process.

74. What is a Multi-threaded Server Configuration?In a Multi-threaded Server Configuration many user processes share a group of server process.

75. What is a Parallel Server option in ORACLE?A configuration for loosely coupled systems where multiple instance share a single physical database is called Parallel Server.

76. Name the ORACLE Background Process?DBWR - Database Writer.LGWR - Log WriterCKPT - Check PointSMON - System MonitorPMON - Process MonitorARCH - ArchiverRECO - RecoverDnnn - Dispatcher, andLCKn - LockSnnn - Server.

77. What Does DBWR do?Database writer writes modified blocks from the database buffer cache to the data files.

78.When Does DBWR write to the database?DBWR writes when more data needs to be read into the SGA and too few database buffers are free. The least recently used data is written to the data files first. DBWR also writes when Checkpoint occurs.

79. What does LGWR do?Log Writer (LGWR) writes redo log entries generated in the redo log buffer of the SGA to on-line Redo Log File.

80. When does LGWR write to the database?LGWR writes redo log entries into an on-line redo log file when transactions commit and the log buffer files are full.

81. What is the function of checkpoint (CKPT)?The Checkpoint (CKPT) process is responsible for signaling DBWR at checkpoints and updating all the data files and control files of the database.

82. What are the functions of SMON?System Monitor (SMON) performs instance recovery at instance start-up. In a multiple instance system (one that uses the Parallel Server), SMON of one instance can also perform instance recovery for other instance that have failed SMON also cleans up temporary segments that are no longer in use and recovers dead transactions skipped during crash and instance recovery because of file-read or off-line errors. These transactions are eventually recovered by SMON when the table space or file is brought back on-line SMON also coalesces free extents within the database to make free space contiguous and easier to allocate.

83. What are functions of PMON?

Process Monitor (PMON) performs process recovery when a user process fails PMON is responsible for cleaning up the cache and Freeing resources that the process was using PMON also checks on dispatcher and server processes and restarts them if they have failed.

84. What is the function of ARCH?Archiver (ARCH) copies the on-line redo log files to archival storage when they are full. ARCH is active only when a database's redo log is used in ARCHIVELOG mode.

85. What is function of RECO?RECOver (RECO) is used to resolve distributed transactions that are pending due to a network or system failure in a distributed database. At timed intervals,the local RECO attempts to connect to remote databases and automatically complete the commit or rollback of the local portion of any pending distributed transactions.

86. What is the function of Dispatcher (Dnnn)?Dispatcher (Dnnn) process is responsible for routing requests from connected user processes to available shared server processes and returning the responses back to the appropriate user processes.

87. How many Dispatcher Processes are created?Atleast one Dispatcher process is created for every communication protocol in use.

88. What is the function of Lock (LCKn) Process?Lock (LCKn) is used for inter-instance locking when the ORACLE Parallel Server option is used.

89. What is the maximum number of Lock Processes used?Though a single LCK process is sufficient for most Parallel Server systemsUp to Ten Locks (LCK0,....LCK9) are used for inter-instance locking.

DATA ACCESS

90. Define Transaction?A Transaction is a logical unit of work that comprises one or more SQL statements executed by a single user.

91. When does a Transaction end?When it is committed or Roll backed.

92. What does COMMIT do?COMMIT makes permanent the changes resulting from all SQL statements in the transaction. The changes made by the SQL statements of a transaction become visible to other user sessions transactions that start only after transaction is committed.

93. What does ROLLBACK do?ROLLBACK retracts any of the changes resulting from the SQL statements in the transaction.

94. What is SAVE POINT?For long transactions that contain many SQL statements, intermediate markers or save points can be declared which can be used to divide a transaction into smaller parts. This allows the option of later rolling back all work performed from the current point in the transaction to a declared save point within the transaction.

95. What is Read-Only Transaction?A Read-Only transaction ensures that the results of each query executed in the transaction are consistent with respect to the same point in time.

96. What is the function of Optimizer?

The goal of the optimizer is to choose the most efficient way to execute a SQL statement.

97. What is Execution Plan?The combination of the steps the optimizer chooses to execute a statement is called an execution plan.

98. What are the different approaches used by Optimizer in choosing an execution plan?Rule-based and Cost-based.

99. What are the factors that affect OPTIMIZER in choosing an Optimization approach?The OPTIMIZER_MODE initialization parameter Statistics in the Data Dictionary the OPTIMIZER_GOAL parameter of the ALTER SESSION command hints in the statement.

100. What are the values that can be specified for OPTIMIZER MODE Parameter?COST and RULE.

101. Will the Optimizer always use COST-based approach if OPTIMIZER_MODE is set to "Cost'?

Presence of statistics in the data dictionary for at least one of the tables accessed by the SQL statements is necessary for the OPTIMIZER to use COST-based approach. Otherwise OPTIMIZER chooses RULE-based approach.

102. What is the effect of setting the value of OPTIMIZER_MODE to 'RULE'?

This value causes the optimizer to choose the rule_based approach for all SQL statements issued to the instance regardless of the presence of statistics.103. What are the values that can be specified for OPTIMIZER_GOAL parameter of the ALTER SESSION Command?

CHOOSE, ALL_ROWS, FIRST_ROWS and RULE.

104. What is the effect of setting the value "CHOOSE" for OPTIMIZER_GOAL, parameter of the ALTER SESSION Command?The Optimizer chooses Cost_based approach and optimizes with the goal of best throughput if statistics for at least one of the tables accessed by the SQL statement exist in the data dictionary. Otherwise the OPTIMIZER chooses RULE_based approach.

105. What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command?This value causes the optimizer to the cost-based approach for all SQL statements in the session regardless of the presence of statistics and to optimize with a goal of best throughput.

106. What is the effect of setting the value 'FIRST_ROWS' for OPTIMIZER_GOAL parameter of the ALTER SESSION command?This value causes the optimizer to use the cost-based approach for all SQL statements in the session regardless of the presence of statistics and to optimize with a goal of best response time.

107. What is the effect of setting the 'RULE' for OPTIMIER_GOAL parameter of the ALTER SESSION Command?This value causes the optimizer to choose the rule-based approach for all SQL statements in a session regardless of the presence of statistics.

108. What is RULE-based approach to optimization?Choosing an executing plan based on the access paths available and the ranks of these access paths.

109. What is COST-based approach to optimization?Considering available access paths and determining the most efficient execution plan based on statistics in the data dictionary for the tables accessed by the statement and their associated clusters and indexes.

PROGRAMMATIC CONSTRUCTS

110. What are the different types of PL/SQL program units that can be defined and stored in ORACLE database?Procedures and Functions, Packages and Database Triggers.

111. What is a Procedure?A Procedure consist of a set of SQL and PL/SQL statements that are grouped together as a unit to solve a specific problem or perform a set of related tasks.112. What is difference between Procedures and Functions?A Function returns a value to the caller where as a Procedure does not.

113. What is a Package?A Package is a collection of related procedures, functions, variables and other package constructs together as a unit in the database.114. What are the advantages of having a Package?Increased functionality (for example, global package variables can be declared and used by any procedure in the package) and performance (for example all objects of the package are parsed compiled, and loaded into memory once)

115. What is Database Trigger?A Database Trigger is procedure (set of SQL and PL/SQL statements) that is automatically executed as a result of an insert in, update to, or delete from a table.

116. What are the uses of Database Trigger?Database triggers can be used to automatic data generation, audit data modifications, enforce complex Integrity constraints, and customize complex security authorizations.

117. What are the differences between Database Trigger and Integrity constraints?

A declarative integrity constraint is a statement about the database that is always true. A constraint applies to existing data in the table and any statement that manipulates the table.

A trigger does not apply to data loaded before the definition of the trigger, therefore, it does not guarantee all data in a table conforms to the rules established by an associated trigger.

A trigger can be used to enforce transitional constraints where as a declarative integrity constraint cannot be used.

DATABASE SECURITY

118. What are Roles?Roles are named groups of related privileges that are granted to users or other roles.

119. What are the uses of Roles?REDUCED GRANTING OF PRIVILEGES - Rather than explicitly granting the same set of privileges to many users a database administrator can grant the privileges for a group of related users granted to a role and then grant only the role to each member of the group.

DYNAMIC PRIVILEGE MANAGEMENT - When the privileges of a group must change, only the privileges of the role need to be modified. The security domains of all users granted the group's role automatically reflect the changes made to the role.

SELECTIVE AVAILABILITY OF PRIVILEGES - The roles granted to a user can be selectively enable (available for use) or disabled (not available for use). This allows specific control of a user's privileges in any given situation.

APPLICATION AWARENESS - A database application can be designed to automatically enable and disable selective roles when a user attempts to use the application.

120. How to prevent unauthorized use of privileges granted to a Role?By creating a Role with a password.121. What is default table space?The Table space to contain schema objects created without specifying a table space name.

122. What is Table space Quota?The collective amount of disk space available to the objects in a schema on a particular table space.

123. What is a profile?Each database user is assigned a Profile that specifies limitations on various system resources available to the user.

124. What are the system resources that can be controlled through Profile?The number of concurrent sessions the user can establish the CPU processing time available to the user's session the CPU processing time available to a single call to ORACLE made by a SQL statement the amount of logical I/O available to the user's session the amount of logical I/O available to a single call to ORACLE made by a SQL statement the allowed amount of idle time for the user's session the allowed amount of connect time for the user's session.

125. What is Auditing?Monitoring of user access to aid in the investigation of database use.

126. What are the different Levels of Auditing?Statement Auditing, Privilege Auditing and Object Auditing.

127. What is Statement Auditing?Statement auditing is the auditing of the powerful system privileges without regard to specifically named objects.

128. What is Privilege Auditing?Privilege auditing is the auditing of the use of powerful system privileges without regard to specifically named objects.

129. What is Object Auditing?Object auditing is the auditing of accesses to specific schema objects without regard to user.

DISTRIBUTED PROCESSING AND DISTRIBUTED DATABASES

130. What is distributed database?A distributed database is a network of databases managed by multiple database servers that appears to a user as single logical database. The data of all databases in the distributed database can be simultaneously accessed and modified.

131. What is Two-Phase Commit?Two-phase commit is mechanism that guarantees a distributed transaction either commits on all involved nodes or rolls back on all involved nodes to maintain data consistency across the global distributed database. It has two phases, a Prepare Phase and a Commit Phase.

132. Describe two phases of Two-phase commit?Prepare phase - The global coordinator (initiating node) ask a participants to prepare (to promise to commit or rollback the transaction, even if there is a failure)

Commit - Phase - If all participants respond to the coordinator that they are prepared, the coordinator asks all nodes to commit the transaction, if all participants cannot prepare, the coordinator asks all nodes to roll back the transaction.

133. What is the mechanism provided by ORACLE for table replication?Snapshots and SNAPSHOT LOGs

134. What is a SNAPSHOT?Snapshots are read-only copies of a master table located on a remote node which is periodically refreshed to reflect changes made to the master table.

135. What is a SNAPSHOT LOG?A snapshot log is a table in the master database that is associated with the master table. ORACLE uses a snapshot log to track the rows that have been updated in the master table. Snapshot logs are used in updating the snapshots based on the master table.

136. What is a SQL * NET?SQL *NET is Oracle’s mechanism for interfacing with the communication protocols used by the networks that facilitate distributed processing and distributed databases. It is used in Clint-Server and Server-Server communications.

DATABASE OPERATION, BACKUP AND RECOVERY

137. What are the steps involved in Database Startup?Start an instance, Mount the Database and Open the Database.

138. What are the steps involved in Database Shutdown?Close the Database, Dismount the Database and Shutdown the Instance.

139. What is Restricted Mode of Instance Startup?An instance can be started in (or later altered to be in) restricted mode so that when the database is open connections are limited only to those whose user accounts have been granted the RESTRICTED SESSION system privilege.

140. What are the different modes of mounting a Database with the Parallel Server?

Exclusive Mode If the first instance that mounts a database does so in exclusive mode, only that Instance can mount the database.

Parallel Mode If the first instance that mounts a database is started in parallel mode, other instances that are started in parallel mode can also mount the database.

141. What is Full Backup?A full backup is an operating system backup of all data files, on-line redo log files and control file that constitute ORACLE database and the parameter.

142. Can Full Backup be performed when the database is open?No.

143. What is Partial Backup?A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.

144.WhatisOn-lineRedoLog?The On-line Redo Log is a set of tow or more on-line redo files that record all committed changes made to the database. Whenever a transaction is committed, the corresponding redo entries temporarily stores in redo log buffers of the SGA are written to an on-line redo log file by the background process LGWR. The on-line redo log files are used in cyclical fashion.

145. What is mirrored on-line Redo Log?A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.

146. What is Archived Redo Log?Archived Redo Log consists of Redo Log files that have archived before being reused.

147. What are the advantages of operating a database in ARCHIVELOG mode over operating it in NO ARCHIVELOG mode?Complete database recovery from disk failure is possible only in ARCHIVELOG mode.Online database backup is possible only in ARCHIVELOG mode.

148. What is Log Switch?The point at which ORACLE ends writing to one online redo log file and begins writing to another is called a log switch.

149. What are the steps involved in Instance Recovery?R_olling forward to recover data that has not been recorded in data files yet has been recorded in the on-line redo log, including the contents of rollback segments.

Rolling back transactions that have been explicitly rolled back or have not been committed as indicated by the rollback segments regenerated in step a. Releasing any resources (locks) held by transactions in process at the time of the failure.

Resolving any pending distributed transactions undergoing a two-phase commit at the time of the instance failure.

Data Base Administration

Introduction to DBA

1. What is a Database instance? Explain

A database instance (Server) is a set of memory structure and background processes that access a set of database files.

The process can be shared by all users.

The memory structure that are used to store most queried data from database. This helps up to improve database performance by decreasing the amount of I/O performed against data file.

2. What is Parallel Server?

Multiple instances accessing the same database (Only In Multi-CPU environments)

3. What is a Schema?

The set of objects owned by user account is called the schema.

4. What is an Index? How it is implemented in Oracle Database?

An index is a database structure used by the server to have direct access of a row in a table.

An index is automatically created when a unique of primary key constraint clause is specified in create table comman (Ver 7.0)

5. What are clusters?

Group of tables physically stored together because they share common columns and are often used together is called Cluster.

6. What is a cluster Key?

The related columns of the tables are called the cluster key. The cluster key is indexed using a cluster index and its value is stored only once for multiple tables in the cluster.

7. What is the basic element of Base configuration of an oracle Database?

It consists of One or more data files. One or more control files. Two or more redo log files.The Database contains Multiple users/schemas One or more rollback segments One or more table spaces Data dictionary tables User objects (table, indexes, views etc.,)The server that access the database consists of SGA (Database buffer, Dictionary Cache Buffers, Redo log buffers, Shared SQL pool) SMON (System MONito) PMON (Process MONitor) LGWR (LoG Write)

DBWR (Data Base Write) ARCH (ARCHiver) CKPT (Check Point) RECO Dispatcher User Process with associated PGS

8. What is a deadlock? Explain.

Two processes waiting to update the rows of a table, which are locked, by the other process then deadlock arises.

In a database environment this will often happen because of not issuing proper rowlock commands. Poor design of front-end application may cause this situation and the performance of server will reduce drastically.

These locks will be released automatically when a commit/rollback operation performed or any one of this processes being killed externally.

MEMORY MANAGEMENT

9. What is SGA? How it is different from Ver 6.0 and Ver 7.0?

The System Global Area in a Oracle database is the area in memory to facilitates the transfer of information between users. It holds the most recently requested structural information between users. It holds the most recently requested structural information about the database.

The structure is Database buffers, Dictionary cache, Redo Log Buffer and Shared SQL pool (ver 7.0 only) area.

10. What is a Shared SQL pool?

The data dictionary cache is stored in an area in SGA called the Shared SQL Pool. This will allow sharing of parsed SQL statements among concurrent users.

11. What is mean by Program Global Area (PGA)?

It is area in memory that is used by a Single Oracle User Process.

12. What is a data segment?

Data segment are the physical areas within a database block in which the data associated with tables and clusters are stored.

13. What are the factors causing the reparsing of SQL statements in SGA?

Due to insufficient Shared SQL pool size.

Monitor the ratio of the reloads takes place while executing SQL statements. If the ratio is greater than 1 then increase the SHARED_POOL_SIZE.

LOGICAL & PHYSICAL ARCHITECTURE OF DATABASE.14. What is Database Buffers?

Database buffers are cache in the SGA used to hold the data blocks that are read from the data segments in the database such as tables, indexes and clusters DB_BLOCK_BUFFERS parameter in INIT.ORA decides the size.

15. What is dictionary cache?

Dictionary cache is information about the database objects stored in a data dictionary table.

16. What is meant by recursive hints?

Number of times processes repeatedly query the dictionary table is called recursive hints. It is due to the data dictionary cache is too small. By increasing the SHARED_POOL_SIZE parameter we can optimize the size of Data Dictionary Cache.

17. What is meant by redo log buffer?

Changes made to entries are written to the on-line redo log files. So that they can be used in roll forward operations during database recoveries. Before writing them into the redo log files, they will first brought to redo log buffers in SGA and LGWR will write into files frequently.LOG_BUFFER parameter will decide the size.

18. How will you swap objects into a different table space for an existing database?

Export the user

Perform import using the command imp system/manager file=export.dmp indexfile=newrite.sql. This will create all definitions into newfile.sql.

Drop necessary objects.

Run the script newfile.sql after altering the tablespaces.

Import from the backup for the necessary objects.

19. List the Optional Flexible Architecture (OFA) of Oracle database? Or how can we organize the table spaces in Oracle database to have maximum performance?

SYSTEM - Data dictionary tables.DATA - Standard operational tables.DATA2- Static tables used for standard operationsINDEXES - Indexes for Standard operational tables.INDEXES1 - Indexes of static tables used for standard operations.TOOLS - Tools table.TOOLS1 - Indexes for tools table.RBS - Standard Operations Rollback Segments,RBS1, RBS2 - Additional/Special Rollback segments.TEMP - Temporary purpose table spaceTEMP_USER - Temporary table space for users.USERS - User table space.20. How will you force database to use particular rollback segment?

SET TRANSACTION USE ROLLBACK SEGMENT rbs_name.

21. What is meant by free extent?

A free extent is a collection of continuous free blocks in table space. When a segment is dropped its extents are reallocated and are marked as free.

22. How free extents are managed in Ver 6.0 and Ver 7.0?

Free extents cannot be merged together in Ver 6.0.Free extents are periodically coalesces with the neighboring free extent inVer 7.0

23.Which parameter in Storage clause will reduce no. of rows per block?

PCTFREE parameter

Row size also reduces no of rows per block.

24. What is the significance of having storage clause?

We can plan the storage for a table as how much initial extents are required, how much can be extended next, how much % should leave free for managing row updations etc.,

25. How does Space allocation table place within a block?

Each block contains entries as followsFixied block headerVariable block headerRow Header,row date (multiple rows may exists)PCTEREE (% of free space for row updation in future)

26. What is the role of PCTFREE parameter is Storage clause?

This is used to reserve certain amount of space in a block for expansion of rows.

27. What is the OPTIMAL parameter?

It is used to set the optimal length of a rollback segment.

28. What is the functionality of SYSTEM table space?

To manage the database level transactions such as modifications of the data dictionary table that record information about the free space usage.

29. How will you create multiple rollback segments in a database?

Create a database that implicitly creates a SYSTEM Rollback Segment in a SYSTEM table space.

Create a Second Rollback Segment name R0 in the SYSTEM table space.

Make new rollback segment available (After shutdown, modify init.ora file and Start database)

Create other tablespaces (RBS) for rollback segments.

Deactivate Rollback Segment R0 and activate the newly created rollback segments.

30. How the space utilisation takes place within rollback segments?

It will try to fit the transaction in a cyclic fashion to all existing extents. Once it found an extent is in use then it forced to acquire a new extent (No. of extents is based on the optimal size)

31. Why query fails sometimes?

Rollback segment dynamically extent to handle larger transactions entry loads.

A single transaction may wipeout all available free space in the Rollback Segment Tablespace. This prevents other user using Rollback segments.

32. How will you monitor the space allocation?

By quering DBA_SEGMENT table/view.

33. How will you monitor rollback segment status?

Querying the DBA_ROLLBACK_SEGS viewIN USE - Rollback Segment is on-line.AVAILABLE - Rollback Segment available but not on-line.OFF-LINE - Rollback Segment off-lineINVALID - Rollback Segment Dropped.NEEDS RECOVERY - Contains data but need recovery or corrupted.PARTLY AVAILABLE - Contains data from an unresolved transaction involving a distributed database.

34. List the sequence of events when a large transaction that exceeds beyond its optimal value when an entry wraps and causes the rollback segment to expand into another extend.

Transaction Begins.

An entry is made in the RES header for new transactions entry

Transaction acquires blocks in an extent of RBS

The entry attempts to wrap into second extent. None is available, so that the RBS must extent.

The RBS checks to see if it is part of its OPTIMAL size.RBS chooses its oldest inactive segment.Oldest inactive segment is eliminated.RBS extentsThe Data dictionary table for space management is updated.Transaction Completes.

35. How can we plan storage for very large tables?

Limit the number of extents in the tableSeparate Table from its indexes.Allocate sufficient temporary storage.

36. How will you estimate the space required by a non-clustered table?

Calculate the total header sizeCalculate the available data space per data blockCalculate the combined column lengths of the average rowCalculate the total average row size.Calculate the average number rows that can fit in a blockCalculate the number of blocks and bytes required for the table.

After arriving the calculation, add 10 % additional space to calculate the initial extent size for a working table.

37. It is possible to use raw devices as data files and what are the advantages over file. System files?

Yes.

The advantages over file system files.

I/O will be improved because Oracle is bye-passing the kernnel which writing into disk.Disk Corruption will be very less.

38. What is a Control file?

Database's overall physical architecture is maintained in a file called control file. It will be used to maintain internal consistency and guide recovery operations. Multiple copies of control files are advisable.

39. How to implement the multiple control files for an existing database?

Shutdown the databaseCopy one of the existing control files to new locationEdit Config ora file by adding new control file.nameRestart the database.

40. What is meant by Redo Log file mirrorring ? How it can be achieved?

Process of having a copy of redo log files is called mirroring.

This can be achieved by creating group of log files together, so that LGWR will automatically writes them to all the members of the current on-line redo log group. If any one group fails then database automatically switch over to next group. It degrades performance.

41. What is advantage of having disk shadowing/ mirroring?

Shadow set of disks save as a backup in the event of disk failure. In most Operating System if any disk failure occurs it automatically switchover to place of failed disk.

Improved performance because most OS support volume shadowing can direct file I/O request to use the shadow set of files instead of the main set of files. This reduces I/O load on the main set of disks.

42. What is use of Rollback Segments In Database?

They allow the database to maintain read consistency between multiple transactions.

43. What is a Rollback segment entry?

It is the set of before image data blocks that contain rows that are modified by a transaction.Each Rollback Segment entry must be completed within one rollback segment.

A single rollback segment can have multiple rollback segment entries.

44. What is hit ratio?

It is a measure of well the data cache buffer is handling requests for data.

Hit Ratio = (Logical Reads - Physical Reads - Hits Misses)/ Logical Reads.

45. When will be a segment released?

When Segment is dropped.When Shrink (RBS only)When truncated (TRUNCATE used with drop storage option)

46. What are disadvantages of having raw devices?

We should depend on export/import utility for backup/recovery (fully reliable)

The tar command cannot be used for physical file backup, instead we can use dd command, which is less flexible and has limited recoveries.

47. List the factors that can affect the accuracy of the estimations?

The space used transaction entries and deleted records do not become free immediately after completion due to delayed cleanout.

Trailing nulls and length bytes are not stored.

Inserts of, updates to and deletes of rows as well as columns larger than a single data block, can cause fragmentation a chained row pieces.

DATABASE SECURITY & ADMINISTRATION

48. What is user Account in Oracle database?

A user account is not a physical structure in Database but it is having important relationship to the objects in the database and will be having certain privileges.

49. How will you enforce security using stored procedures ?

Don't grant user access directly to tables within the application.

Instead grant the ability to access the procedures that access the tables.

When procedure executed it will execute the privilege of procedures owner. Users cannot access tables except via the procedure.

50. What are the dictionary tables used to monitor a database spaces ?

DBA_FREE_SPACEDBA_SEGMENTSDBA_DATA_FILES.

51. What are the responsibilities of a Database Administrator ?

Installing and upgrading the Oracle Server and application tools.Allocating system storage and planning future storage requirements for the database system.Managing primary database structures (tablespaces)Managing primary objects (table,views,indexes)Enrolling users and maintaining system security.Ensuring compliance with Oralce license agreementControlling and monitoring user access to the database.Monitoring and optimising the performance of the database.Planning for backup and recovery of database information.Maintain archived data on tapeBacking up and restoring the database.Contacting Oracle Corporation for technical support.

52. What are the roles and user accounts created automatically with the database ?

DBA - role Contains all database system privileges.

SYS user account - The DBA role will be assigned to this account. All of the basetables and views for the database's dictionary are store in this schema and are manipulated only by ORACLE.

SYSTEM user account - It has all the system privileges for the database and additional tables and views that display administrative information and internal tables and views used by oracle tools are created using this username.54. What are the database administrators utilities avaliable ?

SQL * DBA - This allows DBA to monitor and control an ORACLE database.

SQL * Loader - It loads data from standard operating system files (Flat files) into ORACLE database tables.

Export (EXP) and Import (imp) utilities allow you to move existing data in ORACLE format to and from ORACLE database.

55. What are the minimum parameters should exist in the parameter file (init.ora) ?

DB NAME - Must set to a text string of no more than 8 characters and it will be stored inside the datafiles, redo log files and control files and control file while database creation.

DB_DOMAIN - It is string that specifies the network domain where the database is created. The global database name is identified by setting these parameters (DB_NAME & DB_DOMAIN)

CONTORL FILES - List of control filenames of the database. If name is not mentioned then default name will be used.

DB_BLOCK_BUFFERS - To determine the no of buffers in the buffer cache in SGA.

PROCESSES - To determine number of operating system processes that can be connected to ORACLE concurrently. The value should be 5 (background process) and additional 1 for each user.

ROLLBACK_SEGMENTS - List of rollback segments an ORACLE instance acquires at database startup.

Also optionally LICENSE_MAX_SESSIONS,LICENSE_SESSION_WARNING and LICENSE_MAX_USERS.

56. What is a trace file and how is it created ?

Each server and background process can write an associated trace file. When an internal error is detected by a process or user process, it dumps information about the error to its trace. This can be used for tuning the database.

57. What are roles ? How can we implement roles ?

Roles are the easiest way to grant and manage common privileges needed by different groups of database users.

Creating roles and assigning provies to roles.

Assign each role to group of users. This will simplify the job of assigning privileges to individual users.

58. What are the steps to switch a database's archiving mode between NO ARCHIVELOG and ARCHIVELOG mode ?

1. Shutdown the database instance. 2. Backup the databse 3. Perform any operating system specific steps (optional) 4. Start up a new instance and mount but do not open the databse. 5. Switch the databse's archiving mode.

59. How can you enable automatic archiving ?

Shut the database Backup the database Modify/Include LOG_ARCHIVE_START_TRUE in init.ora file. Start up the databse.

60. How can we specify the Archived log file name format and destination ?

By setting the following values in init.ora file.

LOG_ARCHIVE_FORMAT = arch %S/s/T/tarc (%S - Log sequence number and is zero left paded, %s - Log sequence number not padded. %T - Thread number lef-zero-paded and %t - Thread number not padded). The file name created is arch 0001 are if %S is used.LOG_ARCHIVE_DEST = path.

61. What is the use of ANALYZE command ?

To perform one of these function on an index,table, or cluster:

- to collect statisties about object used by the optimizer and store them in the data dictionary. - to delete statistics about the object used by object from the data dictionary. - to validate the structure of the object. - to identify migrated and chained rows of the table or cluster.

MANAGING DISTRIBUTED DATABASES.

62. How can we reduce the network traffic ? - Replictaion of data in distributed environment. - Using snapshots to replicate data. - Using remote procedure calls.

63. What is snapshots ?

Snapshot is an object used to dynamically replicate data between distribute database at specified time intervals. In ver 7.0 they are read only.

64. What are the various type of snapshots ?

Simple and Complex.

65. Differentiate simple and complex, snapshots ? - A simple snapshot is based on a query that does not contains GROUP BY clauses, CONNECT BY clauses, JOINs, sub-query or snashot of operations. - A complex snapshots contain atleast any one of the above.

66. What dynamic data replication ?

Updating or Inserting records in remote database through database triggers. It may fail if remote database is having any problem.

67. How can you Enforce Refrencial Integrity in snapshots ?

Time the references to occur when master tables are not in use. Peform the reference the manually immdiately locking the master tables. We can join tables in snopshots by creating a complex snapshots that will based on the master tables.

68. What are the options available to refresh snapshots ?

COMPLETE - Tables are completly regenerated using the snapshot's query and the master tables every time the snapshot referenced.FAST - If simple snapshot used then a snapshot log can be used to send the changes to the snapshot tables.FORCE - Default value. If possible it performs a FAST refresh; Otherwise it will perform a complete refresh.

69. what is snapshot log ?

It is a table that maintains a record of modifications to the master table in a snapshot. It is stored in the same database as master table and is only available for simple snapshots. It should be created before creating snapshots.

70. When will the data in the snapshot log be used ?

We must be able to create a after row trigger on table (i.e., it should be not be already available )

After giving table privileges.

We cannot specify snapshot log name because oracle uses the name of the master table in the name of the database objects that support its snapshot log.

The master table name should be less than or equal to 23 characters.

(The table name created will be MLOGS_tablename, and trigger name will be TLOGS name).

72. What are the benefits of distributed options in databases ?

Database on other servers can be updated and those transactions can be grouped together with others in a logical unit.Database uses a two phase commit.

MANAGING BACKUP & RECOVERY

73. What are the different methods of backing up oracle database ?

- Logical Backups - Cold Backups - Hot Backups (Archive log)

74. What is a logical backup ?

Logical backup involves reading a set of databse records and writing them into a file. Export utility is used for taking backup and Import utility is used to recover from backup.

75. What is cold backup ? What are the elements of it ?

Cold backup is taking backup of all physical files after normal shutdown of database. We need to take. - All Data files. - All Control files. - All on-line redo log files. - The init.ora file (Optional)

76. What are the different kind of export backups ?

Full back - Complete databaseIncremental - Only affected tables from last incremental date/full backup date.Cumulative backup - Only affected table from the last cumulative date/full backup date.

77. What is hot backup and how it can be taken ?

Taking backup of archive log files when database is open. For this the ARCHIVELOG mode should be enabled. The following files need to be backed up. All data files. All Archive log, redo log files. All control files.

78. What is the use of FILE option in EXP command ?

To give the export file name.

79. What is the use of COMPRESS option in EXP command ?

Flag to indicate whether export should compress fragmented segments into single extents.

80. What is the use of GRANT option in EXP command ?

A flag to indicate whether grants on databse objects will be exported or not. Value is 'Y' or 'N'.

81. What is the use of INDEXES option in EXP command ?

A flag to indicate whether indexes on tables will be exported.

82. What is the use of ROWS option in EXP command ?Flag to indicate whether table rows should be exported. If 'N' only DDL statements for the databse objects will be created.

83. What is the use of CONSTRAINTS option in EXP command ?

A flag to indicate whether constraints on table need to be exported.

84. What is the use of FULL option in EXP command ?

A flag to indicate whether full databse export should be performed.

85. What is the use of OWNER option in EXP command ?List of table accounts should be exported.

86. What is the use of TABLES option in EXP command ?

List of tables should be exported.

87. What is the use of RECORD LENGTH option in EXP command ?

Record length in bytes.

88. What is the use of INCTYPE option in EXP command ?

Type export should be performed COMPLETE,CUMULATIVE,INCREMENTAL.

89. What is the use of RECORD option in EXP command ?

For Incremental exports, the flag indirects whether a record will be stores data dictionary tables recording the export.

90. What is the use of PARFILE option in EXP command ?

Name of the parameter file to be passed for export.

91. What is the use of PARFILE option in EXP command ?

Name of the parameter file to be passed for export.

92. What is the use of ANALYSE ( Ver 7) option in EXP command ?

A flag to indicate whether statistical information about the exported objects should be written to export dump file.

93. What is the use of CONSISTENT (Ver 7) option in EXP command ?

A flag to indicate whether a read consistent version of all the exported objects should be maintained.

94. What is use of LOG (Ver 7) option in EXP command ?

The name of the file which log of the export will be written.

95.What is the use of FILE option in IMP command ?

The name of the file from which import should be performed.

96. What is the use of SHOW option in IMP command ?

A flag to indicate whether file content should be displayed or not.

97. What is the use of IGNORE option in IMP command ?

A flag to indicate whether the import should ignore errors encounter when issuing CREATE commands.

98. What is the use of GRANT option in IMP command ?

A flag to indicate whether grants on database objects will be imported.

99. What is the use of INDEXES option in IMP command ?

A flag to indicate whether import should import index on tables or not.

100. What is the use of ROWS option in IMP command ?

A flag to indicate whether rows should be imported. If this is set to 'N' then only DDL for database objects will be exectued.

SQL PLUS STATEMENTS

1. What are the types of SQL Statement?

Data Definition Language: CREATE, ALTER, DROP, TRUNCATE, REVOKE, NO AUDIT & COMMIT.Data Manipulation Language: INSERT, UPDATE, DELETE, LOCK TABLE, EXPLAIN PLAN & SELECT.Transactional Control: COMMIT & ROLLBACKSession Control: ALTERSESSION & SET ROLESystem Control: ALTER SYSTEM.

2. What is a transaction?

Transaction is logical unit between two commits and commit and rollback.

3. What is difference between TRUNCATE & DELETE?

TRUNCATE commits after deleting entire table i.e., can’t be rolled back. Database triggers do not fire on TRUNCATE

DELETE allows the filtered deletion. Deleted records can be rolled back or committed.Database triggers fire on DELETE.

4. What is a join? Explain the different types of joins?

Join is a query, which retrieves related columns or rows from multiple tables.

Self Join - Joining the table with itself.Equi Join - Joining two tables by equating two common columns.Non-Equi Join - Joining two tables by equating two common columns.Outer Join - Joining two tables in such a way that query can also retrive rows that do not have corresponding join value in the other table.

5. What is the Subquery?

Subquery is a query whose return values are used in filtering conditions of the main query.

6. What is correlated sub-query?

Correlated sub_query is a sub_query, which has reference to the main query.

7. Explain Connect by Prior?

Retrives rows in hierarchical order.e.g. select empno, ename from emp where.

8. Difference between SUBSTR and INSTR?

INSTR (String1, String 2(n, (m)),INSTR returns the position of the mth occurrence of the string 2 inString1. The search begins from nth position of string1.

SUBSTR (String1 n,m)SUBSTR returns a character string of size m in string1, starting from nth postion of string1.

9. Explain UNION, MINUS, UNION ALL, INTERSECT?

INTERSECT returns all distinct rows selected by both queries.MINUS - returns all distinct rows selected by the first query but not by the second.UNION - returns all distinct rows selected by either queryUNION ALL - returns all rows selected by either query,including all duplicates.

10. What is ROWID?

ROWID is a pseudo column attached to each row of a table. It is 18character long, block no, row number are the components of ROWID.

11. What is the fastest way of accessing a row in a table?

Using ROWID.

CONSTRAINTS----------------------12. What is an Integrity Constraint?

Integrity constraint is a rule that restricts values to a column in a table.13. What is Referential Integrity?

Maintaining data integrity through a set of rules that restrict the values of one or more columns of the tables based on the values of primary key or unique key of the referenced table.

14. What are the usages of SAVEPOINTS?

SAVEPOINTS are used to subdivide a transaction into smaller parts. It enables rolling back part of a transaction. Maximum of five save points are allowed.

15. What is ON DELETE CASCADE?

When ON DELETE CASCADE is specified ORACLE maintains referential integrity by automatically removing dependent foreign key values if a referenced primary or unique key value is removed.

16. What are the data types allowed in a table?

CHAR, VARCHAR2, NUMBER, DATE, RAW, LONG and LONG RAW.

17. What is difference between CHAR and VARCHAR2? What is the maximum SIZE allowed for each type?

CHAR pads blank spaces to the maximum length. VARCHAR2 does not pad blank spaces. For CHAR it is 255 and 2000 for VARCHAR2.

18. How many LONG columns are allowed in a table? Is it possible to use LONG columns in WHERE clause or ORDER BY?

Only one LONG columns is allowed. It is not possible to use LONG column in WHERE or ORDER BY clause.

19. What are the pre requisites? I. To modify data type of a column? ii. To add a column with NOT NULL constraint?

To modify the datatype of a column the column must be empty. To add a column with NOT NULL constrain, the table must be empty.

20. Where the integrity constrints are stored in Data Dictionary?

The integrity constraints are stored in USER_CONSTRAINTS.

21. How will you a activate/deactivate integrity constraints?

The integrity constraints can be enabled or disabled by ALTER TABLE ENABLE constraint/DISABLE constraint.

22. If an unique key constraint on DATE column is created, will it validate the rows that are inserted with SYSDATE ?It won't, Because SYSDATE format contains time attached with it.

23. What is a database link?

Database Link is a named path through which a remote database can be accessed.

24. How to access the current value and next value from a sequence? Is it possible to access the current value in a session before accessing next value?

Sequence name CURRVAL, Sequence name NEXTVAL.

It is not possible. Only if you access next value in the session, current value can be accessed.

25. What is CYCLE/NO CYCLE in a Sequence?

CYCLE specifies that the sequence continues to generate values after reaching either maximum or minimum value. After pan ascending sequence reaches its maximum value, it generates its minimum value. After a descending sequence reaches its minimum, it generates its maximum.

NO CYCLE specifies that the sequence cannot generate more values after reaching its maximum or minimum value.

26. What are the advantages of VIEW?

To protect some of the columns of a table from other users.To hide complexity of a query.To hide complexity of calculations.

27. Can a view be updated/inserted/deleted? If Yes under what conditions?

A View can be updated/deleted/inserted if it has only one base table if the view is based on columns from one or more tables then insert, update and delete is not possible.

28.If a View on a single base table is manipulated will the changes be reflected on the base table?

If changes are made to the tables which are base tables of a view will the changes be reference on the view.

FORMS 3.0 BASIC

1.What is an SQL *FORMS?

SQL *forms is 4GL tool for developing and executing; Oracle based interactive application.

2. What is the maximum size of a form?

255 character width and 255 characters Length.3. Name the two files that are created when you generate the form give the file extension?

INP (Source File) FRM (Executable File)

4. How do you control the constraints in forms?

Select the use constraint property is ON Block definition screen.

BLOCK

5. Committed block sometimes refer to a BASE TABLE? True or False.

False.

6. Can we create two blocks with the same name in form 3.0?

No.

7. While specifying master/detail relationship between two blocks specifying the join condition is a must? True or False.

True.

8. What is a Trigger?

A piece of logic that is executed at or triggered by a SQL *forms event.

9. What are the types of TRIGGERS?

1. Navigational Triggers. 2. Transaction Triggers.

10. What are the different types of key triggers?

Function Key Key-function Key-others Key-startup

11. What is the difference between a Function Key Trigger and Key Function Trigger?

Function key triggers are associated with individual SQL*FORMS function keysYou can attach Key function triggers to 10 keys or key sequences that normally do not perform any SQL * FORMS operations. These keys referred as key F0 through key F9.

12. What does an on-clear-block Trigger fire?

It fires just before SQL * forms the current block.

13. How do you trap the error in forms 3.0?

Using On-Message or On-Error triggers.

14. State the order in which these triggers are executed?

POST-FIELD, ON-VALIDATE-FIELD, POST-CHANGE and KEY-NEXTFLD.KEY-NEXTFLD, POST-CHANGE, ON-VALIDATE-FIELD, POST-FIELD.

15. What is the usage of an ON-INSERT,ON-DELETE and ON-UPDATE TRIGGERS ?

These triggers are executes when inserting, deleting and updating operations are performed and can be used to change the default function of insert, delete or update respectively.

For E.g., instead of inserting a row in a table an existing row can be updated in the same table.

16. When will ON-VALIDATE-FIELD trigger executed?

It fires when a value in a field has been changed and the field status is changed or new and the key has been pressed. If the field status is valid then any further change to the value in the field will not fire the on-validate-field trigger.

17. A query fetched 10 records how many times do a PRE-QUERY Trigger and POST-QUERY Trigger will get executed?

PRE-QUERY fires once. POST-QUERY fires 10 times.

18. What is the difference between ON-VALIDATE-FIELD trigger and a POST-CHANGE trigger?

When you changes the Existing value to null, the On-validate field trigger will fire post change trigger will not fire. At the time of execute-query post-change trigger will fire, on-validate field trigger will not fire.

19. What is the difference between an ON-VALIDATE-FIELD trigger and a trigger?

On-validate-field trigger fires, when the field Validation status New or changed.Post-field-trigger whenever the control leaving form the field, it will fire.

20. What is the difference between a POST-FIELD trigger and a POST-CHANGE trigger?

Post-field trigger fires whenever the control leaving from the filed.Post-change trigger fires at the time of execute-query procedure invoked or filed validation status changed.

21. When is PRE-QUERY trigger executed?

When Execute-query or count-query Package procedures are invoked.22. Give the sequence in which triggers fired during insert operations, when the following 3 triggers are defined at the same block level? a. ON-INSERT b. POST-INSERT c. PRE-INSERT

PRE-INSERT, ON-INSERT & POST-INSERT.

23. Can we use GO-BLOCK package in a pre-field trigger ?

No.

24. Is a Key startup trigger fires as result of a operator pressing a key explicitly?

No.

25. How can you execute the user defined triggers in forms 3.0?

Execute_Trigger (trigger-name)

26. When does an on-lock trigger fire?

It will fires whenever SQL * Forms would normally attempt to lock a row.

26. What is Post-Block is a . a. Navigational Trigger. b. Key trigger c. Transaction Trigger.

Navigational Trigger.

27. What is the difference between keystartup and pre-form ?

Key-startup trigger fires after successful navigation into a form.

Pre-form trigger fires before enter into the form.

28. What is the difference between keystartup and pre-form ?

Key-startup triigger fires after successful navigation into a form.Pre-form trigger fires before enter into the form.

PACKAGE PROCEDURE & FUNCTION-----------------------------------------29. What is a Package Procedure ?

A Package proecdure is built in PL/SQL procedure.

30. What are the different types of Package Procedure ?

1. Restricted package procedure. 2. Unrestricted package proecdure.

31. What is the difference between restricted and unrestricted package procedure ?Restricted package procedure that affects the basic basic functions of SQL * Forms. It cannot used in all triggers execpt key triggers.

Unrestricted package procedure that does not interfere with the basic functions of SQL * Forms it can be used in any triggers.

32. Classify the restricted and unrestricted procedure from the following. a. Call b. User-Exit c. Call-Query d. Up

e. Execute-Query f. Message g. Exit-From h. Post i. Break

a. Call - unrestricted b. User Exit - Unrestricted c. Call_query - Unrestricted d. Up - Restricted e. Execute Query - Restricted f. Message - Restricted g. Exit_form - Restricted h. Post - Restricted i. Break - Unrestricted.

33. Can we use a restricted package procedure in ON-VALIDATE-FIELD Trigger ?

No.

34. What SYNCHRONIZE procedure does ?

It synchoronizes the terminal screen with the internal state of the form.

35. What are the unrestricted procedures used to change the popup screen position during run time ?

Anchor-view Resize -View Move-View.

36. What Enter package procedure does ?

Enter Validate-data in the current validation unit.

37. What ERASE package procedure does ?

Erase removes an indicated global variable.

38. What is the difference between NAME_IN and COPY ?

Copy is package procedure and writes values into a field.Name in is a package function and returns the contents of the variable to which you apply.

38. Identify package function from the following ? 1. Error-Code 2. Break 3. Call 4. Error-text 5. Form-failure 6. Form-fatal 7. Execute-query 8. Anchor_View 9. Message_code

1. Error_Code 2. Error_Text 3. Form_Failure 4. Form_Fatal 5. Message_Code

40. How does the command POST differs from COMMIT ?

Post writes data in the form to the database but does not perform database commitCommit permenently writes data in the form to the database.

41. What the PAUSE package procedure does ?

Pause suspends processing until the operator presses a function key

42. What package procedure is used for calling another form ?

Call (E.g. Call(formname)

43. What package procedure used for invoke sql *plus from sql *forms ?

Host (E.g. Host (sqlplus))

44. Error_Code is a package proecdure ? a. True b. false

False.

45. EXIT_FORM is a restricted package procedure ? a. True b. False

True.

46. When the form is running in DEBUG mode, If you want to examine the values of global variables and other form variables, What package procedure command you would use in your trigger text ?

Break.SYSTEM VARIABLES

47. List the system variables related in Block and Field?

1. System.block_status 2. System.current_block 3. System.current_field 4. System.current_value 5. System.cursor_block 6. System.cursor_field 7. System.field_status.

48. What is the difference between system.current_field and system.cursor_field ?

1. System.current_field gives name of the field. 2. System.cursor_field gives name of the field with block name.

49. The value recorded in system.last_record variable is of type a. Number b. Boolean c. Character.b. Boolean.

User Exits :

50. What is an User Exits ?

A user exit is a subroutine which are written in programming languages using pro*C pro *Cobol , etc., that link into the SQL * forms executable.

51. What are the type of User Exits ?

ORACLE Precompliers user exitsOCI (ORACLE Call Interface)Non-ORACEL user exits.

Page :

52. What do you mean by a page ?

Pages are collection of display information, such as constant text and graphics.

53. How many pages you can in a single form ?

Unlimited.

54. Two popup pages can appear on the screen at a time ? a. True b. False

a. True.55.What is the significance of PAGE 0 in forms 3.0 ? Hide the fields for internal calculation.

56. Deleting a page removes information about all the fields in that page ? a. True. b. False

a. True.

Popup Window :

57. What do you mean by a pop-up window ?

Pop-up windows are screen areas that overlay all or a portion of thedisplay screen when a form is running.

58. What are the types of Pop-up window ?

the pop-up field editor pop-up list of values pop-up pages.

Alert :

59. What is an Alert ?

An alert is window that appears in the middle of the screen overlaying a portion of the current display.

FORMS 4.0

01. Give the Types of modules in a form?

Form Menu Library

02. Write the Abbreviation for the following File Extension 1. FMB 2. MMB 3. PLL

FMB ----- Form Module Binary. MMB ----- Menu Module Binary. PLL ------ PL/SQL Library Module Binary.

03. What are the design facilities available in forms 4.0?

Default Block facility. Layout Editor. Menu Editor. Object Lists. Property Sheets. PL/SQL Editor. Tables Columns Browser. Built-ins Browser.

04. What is a Layout Editor?

The Layout Editor is a graphical design facility for creating and arranging items and boilerplate text and graphics objects in your application's interface.

05. BLOCK

05. What do you mean by a block in forms4.0?

Block is a single mechanism for grouping related items into a functional unit for storing,displaying and manipulating records.

06. Explain types of Block in forms4.0?

Base table Blocks. Control Blocks. 1. A base table block is one that is associated with a specific database table or view. 2. A control block is a block that is not associated with a database table.

ITEMS

07. List the Types of Items?

Text item. Chart item. Check box. Display item. Image item. List item. Radio Group. User Area item.

08. What is a Navigable item?

A navigable item is one that operators can navigate to with the keyboard during default navigation, or that Oracle forms can navigate to by executing a navigationalbuilt-in procedure.

09. Can you change the color of the push button in design time?

No.

10. What is a Check Box?

A Check Box is a two state control that indicates whether a certain condition or value is on or off, true or false. The display state of a check box is always either "checked" or "unchecked".

11. What are the triggers associated with a check box?

Only When-checkbox-activated Trigger associated with a Check box.

PL/SQL

Basiscs of PL/SQL

1. What is PL/SQL ?PL/SQL is a procedural language that has both interactive SQL and procedural programming language constructs such as iteration, conditional branching.

2. What is the basic structure of PL/SQL ?

PL/SQL uses block structure as its basic structure. Anonymous blocks or nested blocks can be used in PL/SQL.

3. What are the components of a PL/SQL block ?

A set of related declarations and procedural statements is called block.

4. What are the components of a PL/SQL Block ?

Declarative part, Executable part and Execption part.

Datatypes PL/SQL

5. What are the datatypes a available in PL/SQL ?

Some scalar data types such as NUMBER, VARCHAR2, DATE, CHAR, LONG, BOOLEAN.Some composite data types such as RECORD & TABLE.

6. What are % TYPE and % ROWTYPE ? What are the advantages of using these over datatypes?

% TYPE provides the data type of a variable or a database column to that variable.

% ROWTYPE provides the record type that represents a entire row of a table or view or columns selected in the cursor.

The advantages are : I. Need not know about variable's data typeii. If the database definition of a column in a table changes, the data type of a variable changes accordingly.

7. What is difference between % ROWTYPE and TYPE RECORD ?

% ROWTYPE is to be used whenever query returns a entire row of a table or view.

TYPE rec RECORD is to be used whenever query returns columns of differenttable or views and variables.

E.g. TYPE r_emp is RECORD (eno emp.empno% type,ename emp ename %type); e_rec emp% ROWTYPE cursor c1 is select empno,deptno from emp; e_rec c1 %ROWTYPE.

8. What is PL/SQL table ?

Objects of type TABLE are called "PL/SQL tables", which are modelled as (but not the same as) database tables, PL/SQL tables use a primary PL/SQL tables can have one column and a primary key.

Cursors

9. What is a cursor ? Why Cursor is required ?

Cursor is a named private SQL area from where information can be accessed. Cursors are required to process rows individually for queries returning multiple rows.

10. Explain the two type of Cursors ?

There are two types of cursors, Implict Cursor and Explicit Cursor.PL/SQL uses Implict Cursors for queries.User defined cursors are called Explicit Cursors. They can be declared and used.

11. What are the PL/SQL Statements used in cursor processing ?

DECLARE CURSOR cursor name, OPEN cursor name, FETCH cursor name INTO or Record types, CLOSE cursor name.

12. What are the cursor attributes used in PL/SQL ?

%ISOPEN - to check whether cursor is open or not % ROWCOUNT - number of rows featched/updated/deleted. % FOUND - to check whether cursor has fetched any row. True if rows are featched. % NOT FOUND - to check whether cursor has featched any row. True if no rows are featched.These attributes are proceded with SQL for Implict Cursors and with Cursor name for Explict Cursors.

13. What is a cursor for loop ?

Cursor for loop implicitly declares %ROWTYPE as loop index,opens a cursor, fetches rows of values from active set into fields in the record and closeswhen all the records have been processed.

eg. FOR emp_rec IN C1 LOOP salary_total := salary_total +emp_rec sal; END LOOP;

14. What will happen after commit statement ? Cursor C1 is Select empno, ename from emp; Begin open C1; loop Fetch C1 into eno.ename; Exit When C1 %notfound;----- commit; end loop; end;

The cursor having query as SELECT .... FOR UPDATE gets closed after COMMIT/ROLLBACK.

The cursor having query as SELECT.... does not get closed even after COMMIT/ROLLBACK.

15. Explain the usage of WHERE CURRENT OF clause in cursors ?

WHERE CURRENT OF clause in an UPDATE,DELETE statement refers to the latest row fetched from a cursor.

Database Triggers

16. What is a database trigger ? Name some usages of database trigger ?

Database trigger is stored PL/SQL program unit associated with a specific database table. Usages are Audit data modificateions, Log events transparently, Enforce complex business rules Derive column values automatically, Implement complex security authorizations. Maintain replicate tables.

17. How many types of database triggers can be specified on a table ? What are they ?

Insert Update Delete

Before Row o.k. o.k. o.k.

After Row o.k. o.k. o.k.

Before Statement o.k. o.k. o.k.

After Statement o.k. o.k. o.k.

If FOR EACH ROW clause is specified, then the trigger for each Row affected by the statement.

If WHEN clause is specified, the trigger fires according to the retruned boolean value.

18. Is it possible to use Transaction control Statements such a ROLLBACK or COMMIT in Database Trigger ? Why ?

It is not possible. As triggers are defined for each table, if you use COMMIT of ROLLBACK in a trigger, it affects logical transaction processing.

19. What are two virtual tables available during database trigger execution ?

The table columns are referred as OLD.column_name and NEW.column_name.For triggers related to INSERT only NEW.column_name values only available.For triggers related to UPDATE only OLD.column_name NEW.column_name values only available.For triggers related to DELETE only OLD.column_name values only available.

20. What happens if a procedure that updates a column of table X is called in a database trigger of the same table ?

Mutation of table occurs.

21. Write the order of precedence for validation of a column in a table ? I. done using Database triggers. ii. done using Integarity Constraints.

I & ii.

Exception :

22. What is an Exception ? What are types of Exception ?

Exception is the error handling part of PL/SQL block. The types are Predefined and user_defined. Some of Predefined execptions are. CURSOR_ALREADY_OPEN DUP_VAL_ON_INDEX NO_DATA_FOUND TOO_MANY_ROWS INVALID_CURSOR INVALID_NUMBER LOGON_DENIED NOT_LOGGED_ON

PROGRAM-ERROR STORAGE_ERROR TIMEOUT_ON_RESOURCE VALUE_ERROR ZERO_DIVIDE OTHERS.

23. What is Pragma EXECPTION_INIT ? Explain the usage ?

The PRAGMA EXECPTION_INIT tells the complier to associate an exception with an oracle error. To get an error message of a specific oracle error.

e.g. PRAGMA EXCEPTION_INIT (exception name, oracle error number)

24. What is Raise_application_error ?

Raise_application_error is a procedure of package DBMS_STANDARD which allows to issue an user_defined error messages from stored sub-program or database trigger.

25. What are the return values of functions SQLCODE and SQLERRM ?

SQLCODE returns the latest code of the error that has occured.SQLERRM returns the relevant error message of the SQLCODE.

26. Where the Pre_defined_exceptions are stored ?

In the standard package.

Procedures, Functions & Packages ;

27. What is a stored procedure ?

A stored procedure is a sequence of statements that perform specific function.

28. What is difference between a PROCEDURE & FUNCTION ?

A FUNCTION is alway returns a value using the return statement. A PROCEDURE may return one or more values through parameters or may not return at all.

29. What are advantages fo Stored Procedures /

Extensibility,Modularity, Reusability, Maintainability and one time compilation.

30. What are the modes of parameters that can be passed to a procedure ?

IN,OUT,IN-OUT parameters.

31. What are the two parts of a procedure ?

Procedure Specification and Procedure Body.

32. Give the structure of the procedure ?

PROCEDURE name (parameter list.....) is local variable declarations

BEGIN Executable statements. Exception. exception handlers

end;

33. Give the structure of the function ?

FUNCTION name (argument list .....) Return datatype is local variable declarations Begin executable statements Exception execution handlers End;

34. Explain how procedures and functions are called in a PL/SQL block ?

Function is called as part of an expression. sal := calculate_sal ('a822'); procedure is called as a PL/SQL statement calculate_bonus ('A822');

35. What is Overloading of procedures ?

The Same procedure name is repeated with parameters of different datatypes and parameters in different positions, varying number of parameters is called overloading of procedures.

e.g. DBMS_OUTPUT put_line

36. What is a package ? What are the advantages of packages ?

Package is a database object that groups logically related procedures.The advantages of packages are Modularity, Easier Applicaton Design, Information. Hiding,. reusability and Better Performance.

37.What are two parts of package ?

The two parts of package are PACKAGE SPECIFICATION & PACKAGE BODY.

Package Specification contains declarations that are global to the packages and local to the schema.Package Body contains actual procedures and local declaration of the procedures and cursor declarations.

38. What is difference between a Cursor declared in a procedure and Cursor declared in a package specification ?

A cursor declared in a package specification is global and can be accessed by other procedures or procedures in a package.A cursor declared in a procedure is local to the procedure that can not be accessed by other procedures.

39. How packaged procedures and functions are called from the following? a. Stored procedure or anonymous block b. an application program such a PRC *C, PRO* COBOL c. SQL *PLUS

a. PACKAGE NAME.PROCEDURE NAME (parameters); variable := PACKAGE NAME.FUNCTION NAME (arguments); EXEC SQL EXECUTE b. BEGIN PACKAGE NAME.PROCEDURE NAME (parameters) variable := PACKAGE NAME.FUNCTION NAME (arguments); END; END EXEC; c. EXECUTE PACKAGE NAME.PROCEDURE if the procedures does not have anyout/in-out parameters. A function can not be called.

40. Name the tables where characteristics of Package, procedure and functions are stored ?

User_objects, User_Source and User_error.

FORMS4.0

12. what is a display item?

Display items are similar to text items but store only fetched or assigned values. Operators cannot navigate to a display item or edit the value it contains.

13. What is a list item?

It is a list of text elements.

14. What are the display styles of list items?

Poplist, No text Item displayed in the list item. Tlist, No element in the list is highlighted.

15. What is a radio Group?

Radio groups display a fixed no of options that are mutually Exclusive .User can select one out of n number of options.

16. How many maximum number of radio buttons can you assign to a radio group?

Unlimited no of radio buttons can be assigned to a radio group

17. can you change the default value of the radio button group at run time?

No.

18.What triggers are associated with the radio group?

Only when-radio-changed trigger associated with radio group

Visual Attributes.

19. What is a visual attribute?

Visual Attributes are the font, color and pattern characteristics of objects that operators see and intract with in our application.

20. What are the types of visual attribute settings?

Custom Visual attributes Default visual attributes Named Visual attributes.

Window

21. What is a window?

A window, byitself , can be thought of as an empty frame. The frame provides a way to intract with the window, including the ability to scroll, move, and resize the window. The content of the window ie. what is displayed inside the frame is determined by the canvas View or canvas-views displayed in the window at run-time.

22. What are the differrent types of windows?

Root window, secondary window.

23. Can a root window be made modal?

No.

24. List the buil-in routine for controlling window during run-time?

Find_window, get_window_property, hide_window, move_window, resize_window, set_window_property, show_View

25. List the windows event triggers available in Forms 4.0?

When-window-activated, when-window-closed, when-window-deactivated,when-window-resized

26. What built-in is used for changing the properties of the window dynamically?

Set_window_property

Canvas-View

27. What is a canvas-view?

A canvas-view is the background object on which you layout the interface items (text-items, check boxes, radio groups, and so on.) and boilerplate objects that operators see and interact with as they run your form. At run-time, operators can see only those items that have been assiged to a specific canvas. Each canvas, in term, must be displayed in a specfic window.

28. Give the equivalent term in forms 4.0 for the following.Page, Page 0?

Page - Canvas-View Page 0 - Canvas-view null.

29. What are the types of canvas-views?

Content View, Stacked View.

30. What is the content view and stacked view?

A content view is the "Base" view that occupies the entire content pane of the window in which it is displayed. A stacked view differs from a content canvas view in that it is not the base view for the window to which it is assigned

31. List the built-in routines for the controlling canvas views during run-time?

Find_canvas Get-Canvas_property Get_view_property Hide_View Replace_content_view Scroll_view Set_canvas_property Set_view_property Show_view

Alert

32. What is an Alert?

An alert is a modal window that displays a message notifies the operator of some application condition

33. What are the display styles of an alert?

Stop, Caution, note

34. Can you attach an alert to a field?

No

35. What built-in is used for showing the alert during run-time?

Show_alert.

36. Can you change the alert messages at run-time?If yes, give the name of th built-in to chage the alert messages at run-time.

Yes. Set_alert_property.

37. What is the built-in function used for finding the alert?

Find_alert

Editors

38. List the editors availables in forms 4.0?

Default editor User_defined editors system editors.

39. What buil-in routines are used to display editor dynamicaly?

Edit_text item show_editor

LOV

40. What is an Lov?

A list of values is a single or multi column selection list displayed ina pop-up window

41. Can you attach an lov to a field at design time?

Yes.

42. Can you attach an lov to a field at run-time? if yes, give the build-in name.

Yes. Set_item_proprety

43. What is the built-in used for showing lov at runtime?

Show_lov

44. What is the built-in used to get and set lov properties during run-time?

Get_lov_property Set_lov_property

Record Group

45. What is a record Group?

A record group is an internal oracle forms data structure that has a simillar column/row frame work to a database table

46. What are the different type of a record group?

Query record group Static record group Non query record group

47. Give built-in routine related to a record groups?

Create_group (Function) Create_group_from_query(Function) Delete_group(Procedure) Add_group_column(Function) Add_group_row(Procedure) Delete_group_row(Procedure) Populate_group(Function) Populate_group_with_query(Function) Set_group_Char_cell(procedure)

48. What is the built_in routine used to count the no of rows in a group?

Get_group _row_count

System Variables

49. List system variables available in forms 4.0, and not available in forms 3.0?

System.cordination_operation System Date_threshold System.effective_Date System.event_window System.suppress_working

50. System.effective_date system variable is read only True/False

False

51. What is a library in Forms 4.0?

A library is a collection of Pl/SQL program units, including user named procedures, functions & packages

52. Is it possible to attach same library to more than one form?

Yes

53. Explain the following file extention related to library?.pll,.lib,.pld

The library pll files is a portable design file comparable to an fmb form file The library lib file is a plat form specific, generated library file comparable to a fmx form file The pld file is Txt format file and can be used for source controlling your library files

Parameter

54. How do you pass the parameters from one form to another form?

To pass one or more parameters to a called form, the calling form must perform the following steps in a trigger or user named routine excute the create_parameter_list built_in function to programatically. Create a parameter list to execute the add parameter built_in procedure to add one or more parameters list. Execute the call_form, New_form or run_product built_in procedure and include the name or id of the parameter list to be passed to the called form.

54. What are the built-in routines is available in forms 4.0 to create and manipulate a parameter list?

Add_parameter Create_Parameter_list Delete_parameter Destroy_parameter_list Get_parameter_attr Get_parameter_list set_parameter_attr

55. What are the two ways to incorporate images into a oracle forms application?

Boilerplate Images Image_items

56. How image_items can be populate to field in forms 4.0?

A fetch from a long raw database column PL/Sql assignment to executing the read_image_file built_in procedure to get an image from the file system.

57. What are the triggers associated with the image item?

When-Image-activated(Fires when the operator double clicks on an image Items) When-image-pressed(fires when the operator selects or deselects the image item)

58. List some built-in routines used to manipulate images in image_item?

Image_add Image_and Image_subtract Image_xor Image_zoom

59. What are the built_in used to trapping errors in forms 4?

Error_type return character Error_code return number Error_text return char Dbms_error_code return no. Dbms_error_text return char

60. What is a predefined exception available in forms 4.0?

Raise form_trigger_failure

61. What are the menu items that oracle forms 4.0 supports?

Plain, Check,Radio, Separator, Magic

FORMS4.5

object groups

01. what ia an object groups?

An object group is a container for a group of objects, you define an object group when you want to package related objects. so that you copy or reference them in another modules.

02. what are the different objects that you cannot copy or reference in object groups?

objects of differnt modules another object groups individual block dependent items program units.

canvas views

03. what are different types of canvas views?

content canvas views stacked canvas views horizontal toolbar vertical toolbar.

04. explain about content canvas views?

Most Canvas views are content canvas views a content canvas view is the "base" view that occupies the entire content pane of the window in which it is displayed.

05. Explain about stacked canvas views?

Stacked canvas view is displayed in a window on top of, or "stacked" on the content canvas view assigned to that same window. Stacked canvas views obscure some part of the underlying content canvas view, and or often shown and hidden programmatically.

06. Explain about horizontal, Vertical tool bar canvas views?

Tool bar canvas views are used to create tool bars for individual windows Horizontal tool bars are display at the top of a window, just under its menu bar. Vertical Tool bars are displayed along the left side of a window

07. Name of the functions used to get/set canvas properties?

Get_view_property, Set_view_property

Windows

07. What is relation between the window and canvas views?

Canvas views are the back ground objects on which you place the interface items (Text items), check boxes, radio groups etc.,) and boilerplateobjects (boxes, lines, images etc.,) that operators interact with us they run your form . Each canvas views displayed in a window.

08. What are the different modals of windows?

Modalless windows Modal windows

09. What are modalless windows?

More than one modelless window can be displayed at the same time, and operators can navigate among them if your application allows them to do so . On most GUI platforms, modelless windows can also be layered to appear either in front of or behind other windows.

10. What are modal windows?

Modal windows are usually used as dialogs, and have restricted functionality compared to modelless windows. On some platforms for example operators cannot resize, scroll or iconify a modal window.

11. How do you display console on a window ?

The console includes the status line and message line, and is displayed at the bottom of the window to which it is assigned.To specify that the console should be displayed, set the console window form property to the name of any window in the form. To include the console, set console window to Null.

12. What is the remove on exit property?

For a modelless window, it determines whether oracle forms hides the window automatically when the operators navigates to an item in the another window.

13. How many windows in a form can have console?

Only one window in a form can display the console, and you cannot chage the console assignment at runtime.

14. Can you have more than one content canvas view attached with a window?

Yes. Each window you create must have atleast one content canvas view assigned to it. You can also create a window that has manipulate contant canvas view. At run time only one of the content canvas views assign to a window is displayed at a time.

15. What are the different window events activated at runtimes?

When_window_activated When_window_closed When_window_deactivated When_window_resized Within this triggers, you can examine the built in system variable system.event_window to determine the name of the window for which the trigger fired.

Modules

27. What are different types of modules available in oracle form?

Form module - a collection of objects and code routines Menu modules - a collection of menus and menu item commands that together make up an application menu library module - a collectio of user named procedures, functions and packages that can be called from other modules in the application

18. What are the default extensions of the files careated by forms modules?

.fmb - form module binary .fmx - form module executable

19. What are the default extentions of the files created by menu module?

.mmb, .mmx

20 What are the default extension of the files created by library module?

The default file extensions indicate the library module type and storage format .pll - pl/sql library module binary

Master Detail

21. What is a master detail relationship?

A master detail relationship is an association between two base table blocks- a master block and a detail block. The relationship between the blocks reflects a primary key to foreign key relationship between the tables on which the blocks are based.

22. What is coordination Event?

Any event that makes a different record in the master block the current record is a coordination causing event.

23. What are the two phases of block coordination?

There are two phases of block coordination: the clear phase and the population phase. During, the clear phase, Oracle Forms navigates internally to the detail block and flushes the obsolete detail records. During the population phase, Oracle Forms issues a SELECT statement to repopulate the detail block with detail records associated witjh the new master record. These operations are accomplished through the execution of triggers.

24. What are Most Common types of Complex master-detail relationships?

There are three most common types of complex master-detail relationships:master with dependent detailsmaster with independent detailsdetail with two masters

25. What are the different types of Delete details we can establish in Master-Details?Cascade

Isolate Non-isolote

26. What are the different defaust triggers created when Master Deletes Property is set to Non-isolated?Master Delets Property Resulting Triggers ---------------------------------------------------- Non-Isolated(the default) On-Check-Delete-Master On-Clear-Details On-Populate-Details

26. Whar are the different default triggers created when Master Deletes Property is set to Cascade?Ans: Master Deletes Property Resulting Triggers --------------------------------------------------- Cascading On-Clear-Details On-Populate-Details Pre-delete

28. What are the different default triggers created when Master Deletes Property is set to isolated?

Master Deletes Property Resulting Triggers ---------------------------------------------------Isolated On-Clear-Details On-Populate-Details

29. What are the Coordination Properties in a Master-Detail relationship?The coordination properties are Deferred Auto-Query These Properties determine when the population phase of blockcoordination should occur.

30. What are the different types of Coordinations of the Master with the Detail block?

42. What is the User-Named Editor?

A user named editor has the same text editing functionality as the default editor, but, becaue it is a named object, you can specify editor attributes such as windows display size, position, and title.

43. What are the Built-ins to display the user-named editor?

A user named editor can be displayed programmatically with the built in procedure SHOW-EDITOR, EDIT_TETITEM independent of any particular text item.

44. What is the difference between SHOW_EDITOR and EDIT_TEXTITEM?

Show editor is the generic built_in which accepts any editor name and takes some input string and returns modified output string. Whereas the edit_textitem built_in needs the input focus to be in the text item before the built_in is excuted.

45. What is an LOV?

An LOV is a scrollable popup window that provides the operator with either a single or multi column selection list.

46. What is the basic data structure that is required for creating an LOV? Record Group.

47. What is the "LOV of Validation" Property of an item? What is the use of it?When LOV for Validation is set to True, Oracle Forms compares the current value of the text item to the values in the first column displayed in the LOV.Whenever the validation event occurs. If the value in the text item matches one of the values in the first column of the LOV, validation succeeds, the LOV is not displayed, and processing continues normally. If the value in the text item does not match one of the values in the first column of the LOV, Oracle Forms displays the LOV and uses the text item value as the search criteria to automatically reduce the list.

48. What are the built_ins used the display the LOV?

Show_lov List_values

49. What are the built-ins that are used to Attach an LOV programmatically to an item?

set_item_property get_item_property (by setting the LOV_NAME property)

50. What are the built-ins that are used for setting the LOV properties at runtime?

get_lov_property set_lov_property

51. What is a record group?

A record group is an internal Oracle Forms that structure that hs a column/row framework similar to a database table. However, unlike database tables, record groups are separate objects that belong to the form module which they are defined.

52. How many number of columns a record group can have?

A record group can have an unlimited number of columns of type CHAR, LONG, NUMBER, or DATE provided that the total number of column does not exceed 64K.

53. What is the Maximum allowed length of Record group Column?

Record group column names cannot exceed 30 characters.

54. What are the different types of Record Groups?

Query Record Groups NonQuery Record Groups State Record Groups

55. What is a Query Record Group?

A query record group is a record group that has an associated SELECT statement. The columns in a query record group derive their default names, data types, had lengths from the database columns referenced in the SELECT statement. The records in query record group are the rows retrieved by the query associated with that record group.

56. What is a Non Query Record Group?

A non-query record group is a group that does not have an associated query, but whose structure and values can be modified programmatically at runtime.

57. What is a Static Record Group?

A static record group is not associated with a query, rather, you define its structure and row values at design time, and they remain fixed at runtime.

58. What are the built-ins used for Creating and deleting groups?

CREATE-GROUP (function) CREATE_GROUP_FROM_QUERY(function) DELETE_GROUP(procedure)

59.What are the built -ins used for Modifying a group's structure?

ADD-GROUP_COLUMN (function) ADD_GROUP_ROW (procedure) DELETE_GROUP_ROW(procedure)

60. POPULATE_GROUP(function) POPULATE_GROUP_WITH_QUERY(function) SET_GROUP_CHAR_CELL(procedure) SET_GROUP_DATE_CELL(procedure) SET_GROUP_NUMBER_CELL(procedure)

61. What are the built-ins used for Getting cell values?

GET_GROUP_CHAR_CELL (function) GET_GROUP_DATE_CELL(function) GET_GROUP_NUMBET_CELL(function)

62. What are built-ins used for Processing rows?

GET_GROUP_ROW_COUNT(function) GET_GROUP_SELECTION_COUNT(function) GET_GROUP_SELECTION(function) RESET_GROUP_SELECTION(procedure) SET_GROUP_SELECTION(procedure) UNSET_GROUP_SELECTION(procedure)

63. What are the built-ins used for finding Object ID function?

FIND_GROUP(function) FIND_COLUMN(function)

64. Use the ADD_GROUP_COLUMN function to add a column to a record group that was created at design time.I) TRUE II)FALSE

II) FALSE

65. Use the ADD_GROUP_ROW procedure to add a row to a static record group

I) TRUE II)FALSE I) FALSE

61. What are the built-in used for getting cell values?

Get_group_char_cell(function)Get_group_date_cell(function)Get_group_number_cell(function)

62. What are the built-ins used for processing rows?

Get_group_row_count(function)Get_group_selection_count(function)Get_group_selection(function)Reset_group_selection(procedure)Set_group_selection(procedure)Unset_group_selection(procedure)

63. What are the built-ins used for finding object ID functions?

Find_group(function)Find_column(function)

64. Use the add_group_column function to add a column to record group that was created at a design time?

False.

65. Use the Add_group_row procedure to add a row to a static record group 1. true or false?

False.

parameters

66. What are parameters?

Parameters provide a simple mechanism for defining and setting the valuesof inputs that are required by a form at startup. Form parameters are variables of type char,number,date that you define at design time.

67. What are the Built-ins used for sending Parameters to forms?

You can pass parameter values to a form when an application executes the call_form, New_form, Open_form or Run_product.

68. What is the maximum no of chars the parameter can store?

The maximum no of chars the parameter can store is only valid for char parameters, which can be upto 64K. No parameters default to 23Bytes and Date parameter default to 7Bytes.

69. How do you call other Oracle Products from Oracle Forms?

Run_product is a built-in, Used to invoke one of the supported oracle tools products and specifies the name of the document or module to be run. If the called product is unavailable at the time of the call, Oracle Forms returns a message to the opertor.

70. How do you reference a Parameter?

In Pl/Sql, You can reference and set the values of form parameters using bind variables syntax. Ex. PARAMETER name = '' or :block.item = PARAMETER Parameter name

71. How do you reference a parameter indirectly?

To indirectly reference a parameter use the NAME IN, COPY 'built-ins to indirectly set and reference the parameters value' Example name_in ('capital parameter my param'), Copy ('SURESH','Parameter my_param')

72. What are the different Parameter types?

Text ParametersData Parameters

73. When do you use data parameter type?

When the value of a data parameter being passed to a called product is always the name of the record group defined in the current form. Data parameters are used to pass data to produts invoked with the run_product built-in subprogram.

74. Can you pass data parametrs to forms?

No.

IMAGES

75. What are different types of images?

Boiler plate imagesImage Items

76. What is the difference between boiler plat images and image items?

Boiler plate Images are static images (Either vector or bit map) that you import from the file system or database to use a grapical elements in your form, such as company logos and maps Image items are special types of interface controls that store and display either vector or bitmap images. Llike other items that store values, image items can be either base table items(items that relate directly to database columns) or control items. The definition of an image item is stored as part of the form module FMB and FMX files,

but no image file is actualy associated with an image item until the item is populate at run time.

77. What are the trigger associated with image items?

When-image-activated fires when the operators double clicks on an image item when-image-pressed fires when an operator clicks or double clicks on an image item

78. What is the use of image_zoom built-in?

To manipulate images in image items.

WORKING WITH MULTIPLE FORMS

79. How do you create a new session while open a new form?

Using open_form built-in setting the session option Ex. Open_form('Stocks ',active,session). when invoke the mulitiple forms with open form and call_form in the same application, state whether the following are true/False

80. Any attempt to navigate programatically to disabled form in a call_form stack is allowed?

False

81. An open form can not be execute the call_form procedure if you chain of called forms has been initiated by another open form?

True

82. When a form is invoked with call_form, Does oracle forms issues a save point?

True

Mouse Operations

83. What are the various sub events a mouse double click event involves?

Double clicking the mouse consists of the mouse down, mouse up, mouse click, mouse down & mouse up events.

84, State any three mouse events system variables?

System.mouse_button_pressedSystem.mouse_button_shift_statesystem.mouse_itemsystem.mouse_canvassystem.mouse_record

OLE

85. What is an OLE?

Object Linking & Embadding provides you with the capability to integrate objects from many Ms-Windows applications into a single compound document creating integrated applications enables you to use the features form .

86. What is the difference between object embedding & linking in Oracle forms?

In Oracle forms, Embedded objects become part of the form module, and linked objects are references from a form module to a linked source file.

87. What is the difference between OLE Server & Ole Container?

An Ole server application creates ole Objects that are embedded or linked in ole Containers ex. Ole servers are ms_word & ms_excell. OLE containers provide a place to store, display and manipulate objects that are created by ole server applications. Ex. oracle forms is an example of an ole Container.

88. What are the different styles of actvation of ole Objects?

In place activationExternal activation

ViSUAL Attributes & property clauses

89. What are visual attributes?

Visual attributes are the font, color, pattern proprities that you set for form and menu objects that appear in your application interface.

90. What is a property clause?

A property clause is a named object that contains a list of properties and thier settings. Once you create a property clause you can base other object on it. An object based on a property can inherit the setting of any property in the clause that makes sense for that object.

91. Can a property clause itself be based on a property clause?

Yes

92. What are the important difference between property clause and visual attributes?

Named visual attributes differed only font, color & pattern attributes, property clauses can contain this and any other properties. You can change the appearance of objects at run time by changing the named visual attributes programatically , property clause assignments cannot be changed programatically. When an object is inheriting from both a property clause and named visual attribute, the named visual attribute settings take precedence, and any visual attribute properties in the class are ignored.

Form Build-ins

93. What is a Text_io Package?

It allows you to read and write information to a file in the file system.

94. What is an User_exit?

Calls the user exit named in the user_exit_string. Invokes a 3Gl programe by name which has been properly linked into your current oracle forms executable.

95. What is synchronize?

It is a terminal screen with the internal state of the form. It updates the screen display to reflect the information that oracle forms has in its internal representation of the screen.

96. What is forms_DDL?

Issues dynamic Sql statements at run time, including server side pl/SQl and DDL

Triggers

97. What is WHEN-Database-record trigger?

Fires when oracle forms first marks a record as an insert or an update. The trigger fires as soon as oracle forms determines through validation that the record should be processed by the next post or commit as an insert or update. c generally occurs only when the operators modifies the first item in the record, and after the operator attempts to navigate out of the item.

98. What are the master-detail triggers?

On-Check_delete_masterOn_clear_detailsOn_populate_details

99. What is the difference between $$DATE$$ & $$DBDATE$$

$$DBDATE$$ retrieves the current database date$$date$$ retrieves the current operating system date.

100. What is system.coordination_operation?

It represents the coordination causing event that occur on the master block in master-detail relation.

101. What are the difference between lov & list item?

Lov is a property where as list item ias an item. A list item can have only one column, lov can have one or more columns.

102. What are the different display styles of list items?

Pop_listText_listCombo box

103. What is pop list?

The pop list style list item appears initially as a single field (similar to a text item field). When the operator selects the list icon, a list of available choices appears.

104. What is a text list?

The text list style list item appears as a rectangular box which displays the fixed number of values. When the text list contains values that can not be displayed, a vertical scroll bar appears, allowing the operator to view and select undisplayed values.

105. What is a combo box?A combo box style list item combines the features found in list and text item. Unlike the pop list or the text list style list items, the combo box style list item will both display fixed values and accept one operator entered value.

106. What are display items?

Display items are similar to text items with the exception that display items only store and display fetched or assigned values.Display items are generaly used as boilerplate or conditional text.

107. What is difference between open_form and call_form?

when one form invokes another form by executing open_form the first form remains displayed,and operators can navigate between the forms as desired. when one form invokes another form by executing call_form,the called form is modal with respect to the calling form.That is, any windows that belong to the calling form are disabled, and operators cannot navigate to them until they first exit the called form.

108. What is new_form built-in?

When one form invokes another form by executing new_form oracle form exits the first form and releases its memory before loading the new form calling new form completely replace the first with the second. If there are changes pending in the first form,the operator will be prompted to save them before the new form is loaded.

109. What is a library?

A library is a collection of subprograms including user named procedures, functions and packages.

110. What is the advantage of the library?

Library's provide a convenient means of storing client-side program units and sharing them among multipule applications. Once you create a library, you can attach it to any other form,menu,or library modules. When you can call library program units from triggers menu items commands and user named routine, you write in the modules to which you have attach the library.when a library attaches another library ,program units in the first library can reference program units in the attached library. Library support dynamic loading-that is library program units are loaded into an application only when needed. This can significantly reduce the run-time memory requirements of an applications.

111. What is strip sources generate options?

Removes the source code from the library file and generates a library files that contains only pcode.The resulting file can be used for final deployment, but can not be subsequently edited in the designer.

ex. f45gen module=old_lib.pll userid=scott/tiger strip_source YES output_file

112.What are the vbx controls?

Vbx control provide a simple mehtod of buildig and enhancing user interfaces.The controls can use to obtain user inputs and display program outputs.vbx control where originally develop as extensions for the ms visual basic environments and include such items as sliders,grides and knobs.

113. What is a timer?

Timer is a "internal time clock" that you can programmatically create to perform an action each time the timer expires.

114. What are built-ins associated with timers?

find_timercreate_timerdelete_timer

115. what are difference between post database commit and post-form commit?

Post-form commit fires once during the post and commit transactions process, after the database commit occures. The post-form-commit trigger fires after inserts,updates and deletes have been posted to the database but before the transactions have been finalished in the issuing the command.The post-database-commit trigger fires after oracle forms issues the commit to finalished transactions.

116. What is a difference between pre-select and pre-query?

Fires during the execute query and count query processing after oracle forms constructs the select statement to be issued, but before the statement is actually issued.

The pre-query trigger fires just before oracle forms issues the select statement to the database after the operator as define the example records by entering the query criteria in enter query mode.

Pre-query trigger fires before pre-select trigger.

117. What is trigger associated with the timer?

When-timer-expired.

118 What is the use of transactional triggers?

Using transactional triggers we can control or modify the default functionality of the oracle forms.

REPORTS

1. What are the different file extensions that are created by oracle reports?

Rep file and Rdf file.

2. From which designation is it preferred to send the output to the printed?

Previewer.

3. Is it possible to disable the parameter from while running the report? Yes

4. What is lexical reference?How can it be created?

Lexical reference is place_holder for text that can be embedded in a sqlstatements.A lexical reference can be created using & before the column orparameter name.

5. What is bind reference and how can it carate?

Bind reference are used to replace the single value in sql,pl/sqlstatements a bind reference can be careated using a (:) before a column ora parameter name.

6.What use of command line parameter cmd file?

It is a command line argument that allows you to specify a file that contain a set of arguments for r20run.

7.Where is a procedure return in an external pl/sql library executed at the client or at the server?

At the client.

8. Where is the external query executed at the client or the server?

At the server.

9. What are the default parameter that appear at run time in the parameter screen?

Destype and Desname.

10. Which parameter can be used to set read level consistency across multiple queries?

Read only.

11. What is term?

The term is terminal definition file that describes the terminal form which you are using r20run.

12. What is use of term?

The term file which key is correspond to which oracle report functions.

13. Is it possible to insert comments into sql statements return in the data model editor?

Yes.

14. If the maximum record retrieved property of the query is set to 10 then a summary value will be calculated?

Only for 10 records.

15. What are the sql clauses supported in the link property sheet?

Where startwith having.

16. To execute row from being displayed that still use column in the row which property can be used?

Format trigger.

17. Is it possible to set a filter condition in a cross product group in matrix reports?

No.

18. If a break order is set on a column would it effect columns which are under the column? No.

19. With which function of summary item is the compute at options required?

percentage of total functions.

20. What is the purpose of the product order option in the column property sheet?

To specify the order of individual group evaluation in a cross products.

21.Can a formula column be obtained through a select statement?

Yes.

22.Can a formula column refered to columns in higher group?

Yes.

23. How can a break order be created on a column in an existing group?

By dragging the column outside the group.

24. What are the types of calculated columns available?

Summary, Formula, Placeholder column.

25. What is the use of place holder column?

A placeholder column is used to hold a calculated values at a specified place rather than allowing is to appear in the actual row where it has to appeared.

26. What is the use of hidden column?

A hidden column is used to when a column has to embedded into boilerplate text.

27. What is the use of break group?

A break group is used to display one record for one group ones.While multiple related records in other group can be displayed.

28. If two groups are not linked in the data model editor, What is the hierarchy between them?

Two group that is above are the left most rank higher than the group that is to right or below it.

29.The join defined by the default data link is an outer join yes or no?

Yes.

30. How can a text file be attached to a report while creating in the report writer?

By using the link file property in the layout boiler plate property sheet.

31. Can a repeating frame be careated without a data group as a base?

No.

32. Can a field be used in a report wihtout it appearing in any data group?

Yes.

33. For a field in a repeating frame, can the source come from the column which does not exist in the data group which forms the base for the frame?

Yes.

34. Is it possible to center an object horizontally in a repeating frame that has a variable horizontal size?

Yes.

35. If yes,how?

By the use anchors.

36. What are the two repeating frame always associated with matrix object?

One down repeating frame below one across repeating frame.

37. Is it possible to split the printpreviewer into more than one region?

Yes.

38. Does a grouping done for objects in the layout editor affect the grouping done in the datamodel editor?

No.

39. How can a square be drawn in the layout editor of the report writer?

By using the rectangle tool while pressing the (Constraint) key.

40. To display the page no. for each page on a report what would be the source & logical page no. or & of physical page no.?

& physical page no.

41. What does the term panel refer to with regard to pages?

A panel is the no. of physical pages needed to print one logical page.

42. What is an anchoring object & what is its use?

An anchoring object is a print condition object which used to explicitly or implicitly anchor other objects to itself.

43. What is a physical page ? & What is a logical page ?

A physical page is a size of a page. That is output by the printer. Thelogical page is the size of one page of the actual report as seen in thePreviewer.

44. What is the frame & repeating frame?

A frame is a holder for a group of fields. A repeating frame is used to display a set of records when the no. of records that are to displayed is not known before.

REPORT TRIGGERS.

45. What are the triggers available in the reports?

Before report, Before form, After form , Between page, After report.

46. Does a Before form trigger fire when the parameter form is suppressed.

Yes.

47. At what point of report execution is the before Report trigger fired?

After the query is executed but before the report is executed and therecords are displayed.

48. Is the After report trigger fired if the report execution fails?

Yes.

49. Give the sequence of execution of the various report triggers?

Before form , After form , Before report, Between page, After report.

50. Is it possible to modify an external query in a report which contains

it?

No.

51. What are the ways to monitor the performance of the report?

Use reports profile executable statement.Use SQL trace facility.

52. Why is it preferable to create a fewer no. of queries in the datamodel.

Because for each query, report has to open a separate cursor and has torebind, execute and fetch data.

53. What are the various methods of performing a calculation in a report ?

1. Perform the calculation in the SQL statements itself.2. Use a calculated / summary column in the data model.

54. Which of the above methods is the faster method?

performing the calculation in the query is faster.

55. Why is a Where clause faster than a group filter or a format trigger?

Because, in a where clause the condition is applied during data retrievalthan after retrieving the data.

56. What is the main diff. bet. Reports 2.0 & Reports 2.5?

Report 2.5 is object oriented.

57. What is the diff. bet. setting up of parameters in reports 2.0 reports2.5?

LOVs can be attached to parameters in the reports 2.5 parameter form.

58. How is link tool operation different bet. reports 2 & 2.5?

In Reports 2.0 the link tool has to be selected and then two fields to belinked are selected and the link is automatically created. In 2.5 the firstfield is selected and the link tool is then used to link the first field tothe second field.

REPORT 2.5 SPECIFIC ISSUES.

59.What are the two types views available in the object navigator(specificto report 2.5)?

View by structure and view by type .

60. Which of the two views should objects according to possession?

view by structure.

61.How is possible to restrict the user to a list of values while enteringvalues for parameters?

By setting the Restrict To List property to true in the parameter propertysheet.

62. How is it possible to select generate a select ste. for the query inthe query property sheet?

By using the tables/columns button and then specifying the table and thecolumn names.

63. If a parameter is used in a query without being previously defined,what diff. exist betw. report 2.0 and 2.5 when the query is applied?

While both reports 2.0 and 2.5 create the parameter, report 2.5 gives amessage that a bind parameter has been created.

64. Do user parameters appear in the data modal editor in 2.5?

No.

65.What is the diff. when confine mode is on and when it is off?

When confine mode is on, an object cannot be moved outside its parent inthe layout.

66. What is the diff. when Flex mode is mode on and when it is off?

When flex mode is on, reports automatically resizes the parent when thechild is resized.

67. How can a button be used in a report to give a drill down facility?

By setting the action asscoiated with button to Execute pl/sql option andusing the SRW.Run_report function.

68. What are the two ways by which data can be generated for a parameter'slist of values?1. Using static values.2. Writing select statement.

69. What are the two panes that Appear in the design time pl/sqlinterpreter?

1.Source pane. 2. Interpreter pane

70. What are three panes that appear in the run time pl/sql interpreter?

1.Source pane. 2. interpreter pane. 3. Navigator pane.

CROSS PRODUCTS AND MATRIX REPORTS

71. How can a cross product be created?

By selecting the cross products tool and drawing a new group surroundingthe base group of the cross products.

72. How can a group in a cross products be visually distinguished from agroup that does not form a cross product?

A group that forms part of a cross product will have a thicker border.

73. Atleast how many set of data must a data model have before a data modelcan be base on it?

Four.

74. Is it possible to have a link from a group that is inside a crossproduct to a group outside ? (Y/N)

No.

75. Is it possible to link two groups inside a cross products after thecross products group has been created?

No.76. What is an user exit used for?

A way in which to pass control (and possibly arguments ) form Oracle reportto another Oracle products of 3 GL and then return control ( and ) backto Oracle reprots.

77. What are the three types of user exits available ?

Oracle Precompiler exits, Oracle call interface,NonOracle user exits.

78. How can values be passed bet. precompiler exits & Oracle callinterface?

By using the statement EXECIAFGET & EXECIAFPUT.

79. How can I message to passed to the user from reports?

By using SRW.MESSAGE function.

Oracle DBA

1. SNAPSHOT is used for [DBA] a] Synonym, b] Table space, c] System server, d] Dynamic datareplication

Ans : D

2. We can create SNAPSHOTLOG for [DBA] a] Simple snapshots, b] Complex snapshots, c] Both A & B, d]Neither A nor BAns : A

3. Transactions per rollback segment is derived from [DBA] a] Db_Block_Buffers, b] Processes, c] Shared_Pool_Size, d] Noneof the above

Ans : B

4. ENQUEUE resources parameter information is derived from [DBA] a] Processes or DDL_LOCKS and DML_LOCKS, b] LOG_BUFFER, c] DB__BLOCK_SIZE..Ans : A

5. LGWR process writes information into a] Database files, b] Control files, c] Redolog files, d] All theabove.Ans : C

6. SET TRANSACTION USE ROLLBACK SEGMENT is used to create userobjects in a particular Tablespace a] True, b] FalseAns : False

7. Databases overall structure is maintained in a file called a] Redolog file, b] Data file, c] Control file, d] All of theabove.Ans : C

8. These following parameters are optional in init.ora parameter fileDB_BLOCK_SIZE, PROCESSES a] True, b] FalseAns : False

9. Constraints cannot be exported through EXPORT command a] True, b] FalseAns : False

10. It is very difficult to grant and manage common privileges needed bydifferent groups of database users using the roles a] True, b] FalseAns : False

11. What is difference between a DIALOG WINDOW and a DOCUMENT WINDOWregarding moving the window with respect to the application window a] Both windows behave the same way as far as moving the window isconcerned. b] A document window can be moved outside the application window whilea dialog window cannot be moved c] A dialog window can be moved outside the application window while adocument window cannot be moved

Ans : C

12. What is the difference between a MESSAGEBOX and an ALERT a] A messagebox can be used only by the system and cannot be used inuser application while an alert can be used in user application also. b] A alert can be used only by the system and cannot be use din userapplication while an messagebox can be used in user application also. c] An alert requires an response from the userwhile a messagebox justflashes a message and only requires an acknowledment from the user d] An message box requires an response from the userwhile a alert justflashes a message an only requires an acknowledment from the userAns : C

13. Which of the following is not an reason for the fact that most of theprocessing is done at the server ? a] To reduce network traffic. b] For application sharing, c] Toimplement business rules centrally, d] None of the aboveAns : D

14. Can a DIALOG WINDOW have scroll bar attached to it ? a] Yes, b] NoAns : B

15. Which of the following is not an advantage of GUI systems ? a] Intuitive and easy to use., b] GUI's can display multipleapplications in multiple windows c] GUI's provide more user interface objects for a developer d] None of the aboveAns :D

16. What is the difference between a LIST BOX and a COMBO BOX ? a] In the list box, the user is restricted to selecting a value from alist but in a combo box the user can type in a value which is not in the list b] A list box is a data entry area while a combo box can be used onlyfor control purposes c] In a combo box, the user is restricted to selecting a value from alist but in a list box the user can type in a value which is not in the list d] None of the aboveAns : A

17. In a CLIENT/SERVER environment , which of the following would not bedone at the client ? a] User interface part, b] Data validation at entry line, c]Responding to user events, d] None of the aboveAns : D

18. Why is it better to use an INTEGRITY CONSTRAINT to validate data in atable than to use a STORED PROCEDURE ? a] Because an integrity constraint is automatically checked while datais inserted into or updated in a table while a stored procedure has to bespecifically invoked b] Because the stored procedure occupies more space in the databasethan a integrity constraint definition c] Because a stored procedure creates more network traffic than aintegrity constraint definitionAns : A

19. Which of the following is not an advantage of a client/server model ? a] A client/server model allows centralised control of data andcentralised implementation of business rules. b] A client/server model increases developer;s productivity c] A client/server model is suitable for all applications d] None of the above.Ans : C

20. What does DLL stands for ? a] Dynamic Language Library b] Dynamic Link Library c] Dynamic Load Library d] None of the aboveAns : B

21. POST-BLOCK trigger is a a] Navigational trigger b] Key trigger c] Transactional trigger d] None of the aboveAns : A

22. The system variable that records the select statement that SQL * FORMSmost recently used to populate a block is a] SYSTEM.LAST_RECORD b] SYSTEM.CURSOR_RECORD c] SYSTEM.CURSOR_FIELD d] SYSTEM.LAST_QUERYAns: D

23. Which of the following is TRUE for the ENFORCE KEY field a] ENFORCE KEY field characterstic indicates the source of the valuethat SQL*FORMS uses to populate the field b] A field with the ENFORCE KEY characterstic should have the INPUTALLOWED charaterstic turned off a] Only 1 is TRUE

b] Only 2 is TRUE c] Both 1 and 2 are TRUE d] Both 1 and 2 are FALSEAns : A

24. What is the maximum size of the page ? a] Characters wide & 265 characters length b] Characters wide & 265 characters length c] Characters wide & 80 characters length d] None of the aboveAns : B

25. A FORM is madeup of which of the following objects a] block, fields only, b] blocks, fields, pages only, c] blocks, fields, pages, triggers and form level procedures, d] Only blocks.Ans : C

26. For the following statements which is true 1] Page is an object owned by a form 2] Pages are a collection of display information such as constant textand graphics. a] Only 1 is TRUE b] Only 2 is TRUE c] Both 1 & 2 are TRUE d] Both are FALSEAns : B

27. The packaged procedure that makes data in form permanent in theDatabase is a] Post b] Post form c] Commit form d] None of the aboveAns : C

28. Which of the following is TRUE for the SYSTEM VARIABLE $$date$$ a] Can be assigned to a global variable b] Can be assigned to any field only during design time c] Can be assigned to any variable or field during run time d] None of the aboveAns : B

29. Which of the following packaged procedure is UNRESTRICTED ? a] CALL_INPUT, b] CLEAR_BLOCK, c] EXECUTE_QUERY, d] USER_EXITAns : D

30. Identify the RESTRICTED packaged procedure from the following a] USER_EXIT, b] MESSAGE, c] BREAK, d] EXIT_FORMAns : D

31. What is SQL*FORMS a] SQL*FORMS is a 4GL tool for developing & executing Oracle basedinteractive

applications. b] SQL*FORMS is a 3GL tool for connecting to the Database. c] SQL*FORMS is a reporting tool d] None of the above.Ans : A

32. Name the two files that are created when you generate a form usingForms 3.0 a] FMB & FMX, b] FMR & FDX, c] INP & FRM, d] None of the aboveAns : C

33. What is a trigger a] A piece of logic written in PL/SQL b] Executed at the arrival of a SQL*FORMS event c] Both A & B d] None of the aboveAns : C

34. Which of the folowing is TRUE for a ERASE packaged procedure 1] ERASE removes an indicated Global variable & releases the memoryassociated with it 2] ERASE is used to remove a field from a page 1] Only 1 is TRUE 2] Only 2 is TRUE 3] Both 1 & 2 are TRUE 4] Both 1 & 2 are FALSEAns : 1

35. All datafiles related to a Tablespace are removed when the Tablespaceis dropped a] TRUE b] FALSEAns : B

36. Size of Tablespace can be increased by a] Increasing the size of one of the Datafiles b] Adding one or more Datafiles c] Cannot be increased d] None of the aboveAns : B

37. Multiple Tablespaces can share a single datafile a] TRUE b] FALSEAns : B

38. A set of Dictionary tables are created a] Once for the Entire Database b] Every time a user is created c] Every time a Tablespace is created d] None of the above

Ans : A

39. Datadictionary can span across multiple Tablespaces a] TRUE b] FALSEAns : B

40. What is a DATABLOCK a] Set of Extents b] Set of Segments c] Smallest Database storage unit d] None of the aboveAns : C

41. Can an Integrity Constraint be enforced on a table if some existingtable data does not satisfy the constraint a] Yes b] NoAns : B

42. A column defined as PRIMARY KEY can have NULL's a] TRUE b] FALSEAns : B

43. A Transaction ends a] Only when it is Committed b] Only when it is Rolledback c] When it is Committed or Rolledback d] None of the aboveAns : C

44. A Database Procedure is stored in the Database a] In compiled form b] As source code c] Both A & B d] Not storedAns : C

45. A database trigger doesnot apply to data loaded before the definitionof the trigger a] TRUE b] FALSEAns : A

46. Dedicated server configuration is a] One server process - Many user processes b] Many server processes - One user process c] One server process - One user process d] Many server processes - Many user processesAns : C

47. Which of the following does not affect the size of the SGA a] Database buffer b] Redolog buffer c] Stored procedure d] Shared poolAns : C

48. What does a COMMIT statement do to a CURSOR a] Open the Cursor b] Fetch the Cursor c] Close the Cursor d] None of the aboveAns : D

49. Which of the following is TRUE 1] Host variables are declared anywhere in the program 2] Host variables are declared in the DECLARE section a] Only 1 is TRUE b] Only 2 is TRUE c] Both 1 & 2are TRUE d] Both are FALSEAns : B

50. Which of the following is NOT VALID is PL/SQL a] Bool boolean; b] NUM1, NUM2 number; c] deptname dept.dname%type; d] date1 date := sysdateAns : B

51. Declare fvar number := null; svar number := 5 Begin goto << fproc>> if fvar is null then << fproc>> svar := svar + 5 end if; End;

What will be the value of svar after the execution ? a] Error b] 10 c] 5 d] None of the above

Ans : A

52. Which of the following is not correct about an Exception ? a] Raised automatically / Explicitly in response to an ORACLE_ERROR b] An exception will be raised when an error occurs in that block c] Process terminates after completion of error sequence.

d] A Procedure or Sequence of statements may be processed.

Ans : C

53. Which of the following is not correct about User_Defined Exceptions ? a] Must be declared b] Must be raised explicitly c] Raised automatically in response to an Oracle error d] None of the above

Ans : C

54. A Stored Procedure is a a] Sequence of SQL or PL/SQL statements to perform specific function b] Stored in compiled form in the database c] Can be called from all client environmets d] All of the above

Ans : D

55. Which of the following statement is false a] Any procedure can raise an error and return an user message anderror number b] Error number ranging from 20000 to 20999 are reserved for userdefined messages c] Oracle checks Uniqueness of User defined errors d] Raise_Application_error is used for raising an user defined error.

Ans : C

56. Is it possible to open a cursor which is in a Package in anotherprocedure ? a] Yes b] No

Ans : A

57. Is it possible to use Transactional control statements in DatabaseTriggers ? a] Yes b] No

Ans : B

58. Is it possible to Enable or Disable a Database trigger ? a] Yes b] No

Ans : A

59. PL/SQL supports datatype(s)

a] Scalar datatype b] Composite datatype c] All of the above d] None of the above

Ans C

60. Find the ODD datatype out a] VARCHAR2 b] RECORD c] BOOLEAN d] RAW

Ans : B

61. Which of the following is not correct about the "TABLE" datatype ? a] Can contain any no of columns b] Simulates a One-dimensional array of unlimited size c] Column datatype of any Scalar type d] None of the above

Ans : A

62. Find the ODD one out of the following a] OPEN b] CLOSE c] INSERT d] FETCH

Ans C

63. Which of the following is not correct about Cursor ? a] Cursor is a named Private SQL area b] Cursor holds temporary results c] Cursor is used for retrieving multiple rows d] SQL uses implicit Cursors to retrieve rows

Ans : B

64. Which of the following is NOT VALID in PL/SQL ? a] Select ... into b] Update c] Create d] Delete

Ans : C

65. What is the Result of the following 'VIK'||NULL||'RAM' ? a] Error b] VIK RAM c] VIKRAM

d] NULL

Ans : C

66. Declare a number := 5; b number := null; c number := 10; Begin if a > b AND a < c then a := c * a; end if; End;What will be the value of 'a' after execution ? a] 50 b] NULL c] 5 d] None of the above

Ans : C67. Does the Database trigger will fire when the table is TRUNCATED ? a] Yes b] No

Ans : B

68. SUBSTR(SQUARE ANS ALWAYS WORK HARD,14,6) will return a] ALWAY b} S ALWA c] ALWAYSAns : C

69. REPLACE('JACK AND JUE','J','BL') will return a] JACK AND BLUE b] BLACK AND JACK c] BLACK AND BLUE d] None of the above

Ans : C

70. TRANSLATE('333SQD234','0123456789ABCDPQRST','0123456789') will return a] 333234 b] 333333 c] 234333 d] None of the above

Ans : A

71. EMPNO ENAME SAL A822 RAMASWAMY 3500 A812 NARAYAN 5000 A973 UMESH 2850 A500 BALAJI 5750

Use these data for the following Questions

Select SAL from EMP E1 where 3 > ( Select count(*) from Emp E2

where E1.SAL > E2.SAL ) will retrieve a] 3500,5000,2500 b] 5000,2850 c] 2850,5750 d] 5000,5750

Ans : A

72. Is it possible to modify a Datatype of a column when column containsdata ? a] Yes b] No

Ans B

73. Which of the following is not correct about a View ? a] To protect some of the columns of a table from other users b] Ocuupies data storage space c] To hide complexity of a query d] To hide complexity of a calculations

Ans : B

74. Which is not part of the Data Definiton Language ? a] CREATE b] ALTER c] ALTER SESSION

Ans : C

75. The Data Manipulation Language statements are a] INSERT b] UPDATE c] SELECT d] All of the above

Ans : D

76. EMPNO ENAME SAL A822 RAMASWAMY 3500 A812 NARAYAN 5000 A973 UMESH A500 BALAJI 5750

Using the above data Select count(sal) from Emp will retrieve a] 1 b] 0 c] 3 d] None of the above

Ans : C

77. If an UNIQUE KEY constraint on DATE column is created, will it acceptthe rows that are inserted with SYSDATE ? a] Will b] Won't

Ans : B

78. What are the different events in Triggers ? a] Define, Create b] Drop, Comment c] Insert, Update, Delete d] All of the above

Ans : C79. What built-in subprogram is used to manipulate images in image items ? a] Zoom_out b] Zoom_in' c] Image_zoom d] Zoom_image

Ans : C

80. Can we pass RECORD GROUP between FORMS ? a] Yes b] No

Ans : A

81. SHOW_ALERT function returns a] Boolean b] Number c] Character d] None of the above

Ans : B

82. What SYSTEM VARIABLE is used to refer DATABASE TIME ? a] $$dbtime$$ b] $$time$$ c] $$datetime$$ d] None of the above

Ans : A

83. :SYSTEM.EFFECTIVE.DATE varaible is a] Read only b] Read & Write c] Write only d] None of the above

Ans : C

84. How can you CALL Reports from Forms4.0 ? a] Run_Report built_in b] Call_Report built_in c] Run_Product built_in d] Call_Product built_in

Ans : C

85. When do you get a .PLL extension ? a] Save Library file b] Generate Library file c] Run Library file d] None of the above

Ans : A

86. What is built_in Subprogram ? a] Stored procedure & Function b] Collection of Subprogram c] Collection of Packages d] None of the above

Ans : D

87. GET_BLOCK property is a a] Restricted procedure b] Unrestricted procedure c] Library function d] None of the above

Ans : D

88. A CONTROL BLOCK can sometimes refer to a BASETABLE ? a] TRUE b] FALSE

Ans : B

89. What do you mean by CHECK BOX ? a] Two state control b] One state control c] Three state control d] none of the above

Ans : C - Please check the Correcness of this Answer ( The correct answeris 2 )

90. List of Values (LOV) supports a] Single column b] Multi column c] Single or Multi column d] None of the above

Ans : C

91. What is Library in Forms 4.0 ? a] Collection of External field b] Collection of built_in packages c] Collection of PL/SQl functions, procedures and packages d] Collection of PL/SQL procedures & triggers

Ans : C

92. Can we use a RESTRICTED packaged procedure in WHEN_TEXT_ITEM trigger ? a] Yes b] No

Ans : B

93. Can we use GO_BLOCK package in a PRE_TEXT_ITEM trigger ? a] Yes b] No

Ans : B

94. What type of file is used for porting Forms 4.5 applications to variousplatforms ? a] .FMB file b] .FMX file c] .FMT file d] .EXE file

Ans : C

95. What built_in procedure is used to get IMAGES in Forms 4.5 ? a] READ_IMAGE_FILE b] GET_IMAGE_FILE c] READ_FILE d] GET_FILE

Ans A

96. When a form is invoked with CALL_FORM does Oracle forms issuesSAVEPOINT ? a] Yes b] No

Ans : A

97. Can we attach the same LOV to different fields in Design time ? a] Yes b] No

Ans : A

98. How do you pass values from one form to another form ? a] LOV

b] Parameters c] Local variables d] None of the above

Ans : B

99. Can you copy the PROGRAM UNIT into an Object group ? a] Yes b] No

Ans : B

100. Can MULTIPLE DOCUMENT INTERFACE (MDI) be used in Forms 4.5 ? a] Yes b] No

Ans : A

101. When is a .FMB file extension is created in Forms 4.5 ? a] Generating form b] Executing form c] Save form d] Run form

Ans : C

102. What is a Built_in subprogram ? a] Library b] Stored procedure & Function c] Collection of Subprograms d] None of the above

Ans : D

103. What is a RADIO GROUP ? a] Mutually exclusive b] Select more than one column c] Above all TRUE d] Above all FALSE

Ans : A

104. Identify the Odd one of the following statements ? a] Poplist b] Tlist c] List of values d] Combo box

Ans : C

105. What is an ALERT ? a] Modeless window b] Modal window c] Both are TRUE d] None of the above

Ans : B

106. Can an Alert message be changed at runtime ? a] Yes b] No

Ans : A

107. Can we create an LOV without an RECORD GROUP ? a} Yes b] No

Ans : B

108. How many no of columns can a RECORD GROUP have ? a] 10 b] 20 c] 50 d] None of the above

Ans D

109. Oracle precompiler translates the EMBEDDED SQL statemens into a] Oracle FORMS b] Oracle REPORTS c] Oracle LIBRARY d] None of the above

Ans : D

110. Kind of COMMENT statements placed within SQL statements ? a] Asterisk(*) in column ? b] ANSI SQL style statements(...) c] C-Style comments (/*......*/) d] All the above

Ans : D

111. What is the appropriate destination type to send the output to aprinter ? a] Screen b] Previewer c] Either of the above d] None of the above

Ans : D

112. What is TERM ? a] TERM is the terminal definition file that describes the terminalfrom which you are using R20RUN ( Reports run time ) b] TERM is the terminal definition file that describes the terminal

from which you are using R20DES ( Reports designer ) c] There is no Parameter called TERM in Reports 2.0 d] None of the above

Ans : A

113. If the maximum records retrieved property of a query is set to 10,then a summary value will be calculated a] Only for 10 records b] For all the records retrieved c] For all therecords in the referenced table d] None of the above

Ans : A

114. With which function of a summary item in the COMPUTE AT optionrequired ? a] Sum b] Standard deviation c] Variance d] % of Total function

Ans : D

115. For a field in a repeating frame, can the source come from a columnwhich does not exist in the datagroup which forms the base of the frame ? a] Yes b] No

Ans : A

116. What are the different file extensions that are created by OracleReports ? a] .RDF file & .RPX file b] .RDX file & .RDF file c] .REP file & .RDF file d] None of the above

Ans : C

117. Is it possible to Disable the Parameter form while running the report? a] Yes b] No

Ans : A118.What are the SQL clauses supported in the link property sheet ? a] WHERE & START WITH b] WHERE & HAVING c} START WITH & HAVING d] WHERE, START WITH & HAVING

Ans : D119. What are the types of Calculated columns available ? a] Summary, Place holder & Procedure column b] Summary, Procedure & Formula columns c] Procedure, Formula & Place holder columns d] Summary, Formula & Place holder columns

Ans.: D120. If two groups are not linked in the data model editor, what is thehierarchy between them? a] There is no hierarchy between unlinked groups b] The group that is right ranks higher than the group that is to theleft c] The group that is above or leftmost ranks higher than the groupthat is to right or below it d] None of the above

Ans : C

121. Sequence of events takes place while starting a Database is a] Database opened, File mounted, Instance started b] Instance started, Database mounted & Database opened c] Database opened, Instance started & file mounted d] Files mounted, Instance started & Database opened

Ans : B122. SYSTEM TABLESPACE can be made off-line a] Yes b] No

Ans : B123. ENQUEUE_RESOURCES parameter information is derived from a] PROCESS or DDL_LOCKS & DML_LOCKS b] LOG BUFFER c] DB_BLOCK_SIZE d] DB_BLOCK_BUFFERS

Ans : A124. SMON process is used to write into LOG files a] TRUE b] FALSE

Ans : B125. EXP command is used a] To take Backup of the Oracle Database b] To import data from the exported dump file c] To create Rollback segments d] None of the above

Ans : A126. SNAPSHOTS cannot be refreshed automatically a] TRUE b] FALSE

Ans : B127. The User can set Archive file name formats a] TRUE b] FALSE

Ans : A

128. The following parameters are optional in init.ora parameter fileDB_BLOCK_SIZE, PROCESS a} TRUE b] FALSEAns : B129. NOARCHIEVELOG parameter is used to enable the database in Archievemode a] TRUE b] FALSE

Ans : B130. Constraints cannot be exported through Export command? a] TRUE b] FALSE

Ans: B131. It is very difficult to grant and manage common priveleges needed byDifferent groups of Database users using roles a] TRUE b] FALSE

Ans: B132. The status of the Rollback segment can be viewed through a] DBA_SEGMENTS b] DBA_ROLES c] DBA_FREE_SPACES d] DBA_ROLLBACK_SEG

Ans: D

133. Explicitly we can assign transaction to a rollback segment a] TRUE B] FALSE

Ans: A

134. What file is read by ODBC to load drivers ? a] ODBC.INI b] ODBC.DLL c] ODBCDRV.INI d] None of the above

Ans: A

Quiz – 1

1)Display the names of all the employees and their experience in years.SELECT ENAME,ROUND(MONTHS_BETWEEN(SYSDATE,HIREDATE)/12) AS EXPERINCE FROM EMP

2)Display the employee name and his manager's name.ANS. select a.ename as employee,b.ename as managerfrom emp a,emp bwhere b.empno=a.mgr

3)Display the employee's name, department's name ,grade and manager's name.SQL> SELECT a.ENAME,DNAME,s.grade,B.ENAME 2 FROM emp a,EMP B,DEPT D,salgrade s 3 WHERE a.mgr=b.empno4 AND A.DEPTNO=D.DEPTNO5 And a.sal between s.losal and s.hisal

5 /

4)Display the emp name and salary those earn more than the average salary of the company. select ename,sal from emp where sal>(select avg(sal) from emp);

5)Display all the employees who earn more than their manager's salary.SELECT A.EMPNO FROM EMP A,EMP BWHERE B.EMPNO=A.MGRAND A.SAL>B.SAL

6)Display all the employees whose grade is the same as that of JONES.

Select empno,ename fromEmp A,SALGRADE S,(select grade from salgrade,emp Where sal between LOsal and HIsal And ename='JONES') BWHERE A.SAL BETWEEN S.LOSAL AND S.HISALAND S.GRADE=B.GRADEAND A.ENAME <>'JONES'OR

Select empno,ename fromEmp A,SALGRADE SWHERE A.SAL BETWEEN S.LOSAL AND S.HISALAND S.GRADE=(select grade from salgrade,emp Where sal between LOsal and HIsal And ename='JONES')AND A.ENAME <>'JONES'

7)Display all employee names and their salaries whose salary is not in the range on 1500 and 2850 The Column Heading to be displayed as

Emp Monthly Name Salary

---- ------SQL> column ename heading 'Emp|Name'SQL> column sal heading 'Monthly|Salary' SQL> select ename,sal 2 from emp 3 where sal not between 1500 and 2850;

8)Display the name of the employee who don't have any manager.select ename from emp where mgr is null;

9)Display the name ,salary and commission for all employees whose commission amount is greater than their salary increased by 10%select ename,sal,comm from emp where comm >(1.1*sal);

10)Display the Ename,salary and salary increased by 15% expressed as a whole number.Label the column New Salary.In addition to this display the Increase of salary over the previous one.For Example.

ENAME SAL NEWSAL INCREASE----- --- ------ -------KING 5000 5500 500

SELECT ENAME,SAL,ROUND(SAL*1.15) AS NEWSAL,ROUND(SAL*1.15)-sal AS INCREASEFROM EMP

11)Display the Employee name ,hiredate, salary review date which is the first Monday after 6 months of the service.

Ename Hiredate Review----- -------- ------KING 17-NOV-81 Monday, the Twenty-Forth of May,1982

select ename as Ename, hiredate as Hiredate, to_char(next_day(add_months(hiredate,6),'monday'),'Day",the" ddsp "of" month rrrr')as Review from emp/

12)Create a query that will display the employee name ,dept number and all the employees name that work in tha same dept as a given employee.

select a.ename,a.deptno,b.enamefrom emp a,emp bwhere b.deptno=a.deptnoand a.ename !=b.enameorder by a.deptno,a.ename

13) Display the Job and the no. of persons working in each job type.select job,count(job) from emp group by job;

14) Display dept name,location,number of employees and the average salary for all employees in that dept.

select dname,loc,count(empno),avg(sal)from emp,deptwhere emp.deptno(+)=dept.deptnogroup by dname,loc

15) Display the empname,salary of all employees who report to KING. select a.ename,a.sal from emp a,emp b where b.empno=a.mgr and b.ename ='KING' /

select ename,sal+nvl(comm,0),job,locfrom emp,deptwhere emp.deptno=dept.deptnoand sal+nvl(comm,0)>(select sal+nvl(comm,0)from emp where ename=’JONES’);

EXERCISE 1Quiz - 2

1.Display current date and 78 days after.SELECT SYSDATE, SYSDATE+78 FROM DUAL;

2. Display the current date in the following fashion.Today's date is : Jan 4 1998.SELECT TO_CHAR(SYSDATE,' "Today''s date is :" MON D YYYY') FROM DUAL

3. Display Employee name and Job information from employee in the following fashion.SMITH Works as CLERK.select ename||' Works as '||job from emp

4. Display all the information from department table where second character of city name is 'A'.SELECT * FROM DEPT WHERE LOC LIKE '_A%'

5. Display rowid, employee number from employee table.SQL> SELECT ROWID,EMPNO FROM EMP;

6. Display rowid, row number, deptno from department table.SQL> SELECT ROWID,ROWNUM,DEPTNO FROM DEPT 2 /

7. Display the last date in Feb-97

select LAST_DAY(to_date('FEB-97','MON-YY')) FROM DUAL

8. Display logged on user name in the following fashion.Current User Name is : SCOTTselect 'Current User Name is: ' || user from dual;

9. Display 'YOU ARE GOOD IN SQL' text as 'You Are Good In Sql' in a Select statement.SELECT INITCAP('U ARE GOOD IN SQL')FROM DUAL;

10. Display current date and 78 days before.SQL> SELECT SYSDATE,SYSDATE-78 FROM DUAL;

Group Functions===============

1. Select maximum, minimum salary in employee table.select max(sal),min(sal) from emp;

2. Select minimum salary,commission in employee table for deptno 20. select sal,comm from emp where deptno=20 and sal=(select min(sal) from emp where deptno=20)

3. Select employee number, employee name, department number whose sum of salary and commission greater than 2500.

select empno, ename, deptno from empwhere empno in (select empno from emp a having sum(sal+comm) > 2500 group by empno)

4.Select employee number, employee name, employee experience in years from employee table.select empno,ename,round(months_between(sysdate,hiredate)/12) from emp;

5. Select employee number , employee name hired in the month of july.select empno,ename from emp where to_char(hiredate,'MON')='JUL'

6.Select employee name ,Hiredate in the format of "2nd of july 1997" for deptno 10 and 20.SELECT ENAME,TO_CHAR(HIREDATE,'ddth "of" month rrrr')from empwhere deptno in(10,20)

7.Display employee names in lower case whose salary is greater than 2000 and less than 2800.

select lower(ename) from emp where sal between 2000 and 2800;

8.Select the number of employees who has no commission .select count(empno) from emp where comm is null;

9.Select employee name whose job is Manager or Clerk and Salary greater than 1000 and commission greater than 100 and deptno is either 10 or 20.

select ename from empwhere job in('MANAGER','CLERK')AND SAL >1000AND COMM>100AND DEPTNO IN(10,20);

10.Select employee names in an alphabetical order.select ename from emp order by ename;

SQL Exercise (Simple Joins)

1. Display employee number, employee name, department name, location from employee and department tables.

Select empno,ename,dname,loc from emp,dept where emp.deptno(+)=dept.deptno

2. Display employee number, employee name, salary + comm as TOTAL, location from employee and department tables.

Select empno,ename,dname,loc,sum(sal+comm) as total from emp,deptwhere emp.deptno(+)=dept.deptnogroup by empno,ename,dname,loc/

3. Display employee name, location from employee and department tables.select ename,loc from emp,deptwhere emp.deptno=dept.deptno

4. Diplay employee name, department name, job from employee and department tables who job is CLERK.select ename,dname,job from emp,deptwhere emp.deptno=dept.deptnoand job='CLERK'

5. Display employee name, deptno, dname from employee and department table where location is DALLAS.select ename,A.dEPTNO,DNAME from emp A,deptwhere A.deptno=dept.deptnoand LOC='DALLAS'

6. Display employee number, name, address and city from employee, employee address tables.Select a.empno,a.ename,b.address,b.city from emp a,address bWhere a.empno=b.empno;

7. Display employee nmae, address from employee and employee address tables who lives in zip code 75039

Select a.empno,a.ename,b.address,b.city from emp a,address bWhere a.empno=b.empnoAnd b.zip_code=75039;

8. Display employee name, department name, location who were getting comm as null.

Select ename,dname,loc from emp,deptWhere emp.deptno=dept.deptnoAnd comm is null;

9. Display first 3 characters of employee name, job, sal, comm, location from employee and department tables who works in department 20 or 30, salary should be more than 1000 comm as not null.

Select substr(ename,1,3),job,sal,comm,locFrom emp,dept Where emp.deptno=dept.deptnoAnd emp.deptno in(20,30)And sal >1000And comm is not null;

10. Display location, department name, length of location, length of department name for employee numbers 1001, 1008, 1009.

Select loc,dname,length(loc),length(dname)From emp,dept where emp.deptno=dept.deptnoAnd empno in (1001,1008,1009);

Exercise (Group By Clause)

1. Display deptno, number of employee works in each department.

select dept.deptno,count(empno) from emp,deptwhere emp.deptno(+)=dept.deptnogroup by dept.deptno

2. Display job, number of employees works in each category.select job,count(empno) from empgroup by job/

3. Display job and averge salary paid for each jobs in the company.select job,avg(sal) from empgroup by job/

4. Display location and sum of the salary spending for employees on that location respectively.

select loc,sum(sal) from emp,deptwhere emp.deptno(+)=dept.deptnogroup by loc

5. Select minimum salary, maximum salary in each department.Select min(sal),max(sal) from emp group by deptno;

6. Select department number, dname, average salary for each department.Select dept.deptno,dname,avg(sal) from emp,deptWhere dept.deptno=emp.deptno(+)Group by dept.deptno

7. Select job, number of employees working in that job, maximum and minimum salary for each job.

Select job,count(empno),max(sal),min(sal)From emp group by job

8.Select department number, name where atleast 3 employees works.

Select deptno,dname from deptWhere deptno in(select deptno from emp having count(empno) >=3Group by deptno)/9. Select department name, location where the average salary in each department more than 1600.

select dname,loc from deptwhere dept.deptno in (select deptno from emp having avg(sal)>1600 group by deptno)

10. Select department name, job and sum of salary by each job with in the department.Select dname,job,sum(sal) from emp,deptWhere emp.deptno=dept.deptnoGroup by dname,job

Exercise ( Use SQL Functions )

1. Display the following text in lowercase ‘DISPLAY EXAMPLE IN LOWERCASE'SELECT LOWER('DISPLAY EXAMPLE IN LOWERCASE') FROM DUAL;

2. Display the following text in uppercase ‘you are great’. SELECT UPPER('you are great') FROM DUAL;

3. Write a select statement to add 123 and 786. SELECT SUM(123+786) FROM DUAL;

4. What is the length of ‘CURRENT’ string. SELECT LENGTH('CURRENT') FROM DUAL;

5. Display the current username. SELECT USER FROM DUAL;

6. Display ‘DOCTOR’ from ‘JOHN IS A DOCTOR’ string. SELECT SUBSTR('JOHN IS A DOCTOR',11,6) FROM DUAL;

7. Display Day of 'July-10-1998' SELECT TO_CHAR(TO_DATE('July-10-1998','Month-dd-rrrr'),'DAY') FROM DUAL

8. Display number of days till today from your date of birth. select sysdate-TO_DATE('04-SEP-1977','DD-MON-YYYY') FROM DUAL

9. Display the date after 18 months from today. SELECT ADD_MONTHS(SYSDATE,18) FROM DUAL;

10.Display employee information if employee id is an even number select * from emp where mod(empno,2)=0;

Exercise ( Date functions from Dual Table)

1.Display Current date SELECT SYSDATE FROM DUAL

2.Display Current Time. SELECT TO_CHAR(SYSDATE,'HH:MI:SS') FROM DUAL;

3.Display current user name. SELECT USER FROM DUAL;

4.Display Current date in July 3 1997 format SELECT TO_CHAR(SYSDATE,'Month dd RRRR') FROM DUAL;

5.Display Current date and the date after 78 days. SELECT SYSDATE,SYSDATE+78 FROM DUAL;

6.Display Current date, day, 70 days after current date and its day also. SELECT SYSDATE,TO_CHAR(SYSDATE,'DAY'),SYSDATE+70,TO_CHAR(SYSDATE+70,'DAY') FROM DUAL;

7.Display the months between ‘JAN-10-65’ and ‘JUN-23-98’ take the input in specified format.select (months_between(to_date('JAN-10-65','MON-DD-RR' ),to_date('JUN-23-98','MON-DD-RR') ))from dual/ 8.Display the current date as Today’s date is : current date from system. SELECT 'Today''s date is : '||sysdate from dual;

9.Display Current date, time and user name. select sysdate,to_char(sysdate,'hh:mi:ss'),user from dual;

10.Display the day like Sunday or what for this date ‘July 4 1998’ select to_char(to_date('July 4 1998' ,'fmMonthfmdd yyyy'),'Day') from dual

ROWNUMBERING WITH AN ORDER BY CLAUSE

One of the most often uses of the pseudo column rownum is to provide serial numbers to the records in a query. This feature is widely used in reports to represent systematic display of information.For instance

Listing ASelect rownum, ename, empnofrom emp10;

Table A

ROWNUM ENAME EMPNO--------- ---------- --------- 1 KING 7839 2 BLAKE 7698 3 CLARK 7782 4 JONES 7566 5 MARTIN 7654

However, when we order this statement the rownum gets disturbed as shown below ( Listing B and Table B).

Listing Bselect rownum, ename, empno from emp10order by ename;

Table BROWNUM ENAME EMPNO--------- ---------- --------- 2 BLAKE 7698 3 CLARK 7782 4 JONES 7566 1 KING 7839 5 MARTIN 7654

As we can see from above the employee names did get ordered but the rownum also got the wrong order. The desired result was BLAKE having rownum 1 , CLARK having a rownum of 2 and so on. To achieve this we have to outer join this table with dual that process forces a implicit order on the rownum as shown below ( Listing C, Table C).

Listing Cselect rownum, ename, empno from emp10 a , dual dwhere a.ename = d.dummy (+)order by ename;

Table CROWNUM ENAME EMPNO------- ---------- --------- 1 BLAKE 7698 2 CLARK 7782 3 JONES 7566 4 KING 7839 5 MARTIN 7654

The trick is to do an outer join with the column that you want to order and this process does not disturb the rownum order. In addition to that if the column is of number datatype then one should make sure to use TO_CHAR datatype conversion function.

What are the difference between DDL, DML and DCL commands?DDL is Data Definition Language statements. Some examples:

CREATE - to create objects in the database

ALTER - alters the structure of the database

DROP - delete objects from the database

TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed

COMMENT - add comments to the data dictionary

GRANT - gives user's access privileges to database

REVOKE - withdraw access privileges given with the GRANT command

DML is Data Manipulation Language statements. Some examples:

SELECT - retrieve data from the a database

INSERT - insert data into a table

UPDATE - updates existing data within a table

DELETE - deletes all records from a table, the space for the records remain

CALL - call a PL/SQL or Java subprogram

EXPLAIN PLAN - explain access path to data

LOCK TABLE - control concurrency

DCL is Data Control Language statements. Some examples:

COMMIT - save work done

SAVEPOINT - identify a point in a transaction to which you can later roll back

ROLLBACK - restore database to original since the last COMMIT

SET TRANSACTION - Change transaction options like what rollback segment to use

How does one escape special characters when building SQL queries?

The LIKE keyword allows for string searches. The '_' wild card character is used to match exactly one character, '%' is used to match zero or more occurrences of any characters. These characters can be escaped in SQL. Example: SELECT name FROM emp WHERE id LIKE '%\_%' ESCAPE '\';

Use two quotes for every one displayed. Example: SELECT 'Franks''s Oracle site' FROM DUAL; SELECT 'A ''quoted'' word.' FROM DUAL; SELECT 'A ''''double quoted'''' word.' FROM DUAL;

How does one eliminate duplicates rows from a table?

Choose one of the following queries to identify or remove duplicate rows from a table leaving only unique records in the table:

Method 1: SQL> DELETE FROM table_name A WHERE ROWID > ( 2 SELECT min(rowid) FROM table_name B 3 WHERE A.key_values = B.key_values);Method 2: SQL> create table table_name2 as select distinct * from table_name1; SQL> drop table_name1; SQL> rename table_name2 to table_name1; SQL> -- Remember to recreate all indexes, constraints, triggers, etc on table... Method 3: (thanks to Dennis Gurnick) SQL> delete from my_table t1 SQL> where exists (select 'x' from my_table t2 SQL> where t2.key_value1 = t1.key_value1 SQL> and t2.key_value2 = t1.key_value2 SQL> and t2.rowid > t1.rowid);Note: One can eliminate N^2 unnecessary operations by creating an index on the joined fields in the inner loop (no need to loop through the entire table on each pass by a record). These will speed-up the deletion process.

Note 2: If you are comparing NOT-NULL columns, use the NVL function. Remember that NULL is not equal to NULL. This should not be a problem as all key columns should be NOT NULL by definition.

How does one generate primary key values for a table?

Create your table with a NOT NULL column (say SEQNO). This column can now be populated with unique values: SQL> UPDATE table_name SET seqno = ROWNUM;

or use a sequences generator: SQL> CREATE SEQUENCE sequence_name START WITH 1 INCREMENT BY 1; SQL> UPDATE table_name SET seqno = sequence_name.NEXTVAL;Finally, create a unique index on this column.

How does one get the time difference between two date columns?

Look at this example query: select floor(((date1-date2)*24*60*60)/3600) || ' HOURS ' || floor((((date1-date2)*24*60*60) - floor(((date1-date2)*24*60*60)/3600)*3600)/60) || ' MINUTES ' || round((((date1-date2)*24*60*60) - floor(((date1-date2)*24*60*60)/3600)*3600 - (floor((((date1-date2)*24*60*60) - floor(((date1-date2)*24*60*60)/3600)*3600)/60)*60))) || ' SECS ' time_difference from ...

If you don't want to go through the floor and ceiling math, try this method (contributed by Erik Wile): select to_char(to_date('00:00:00','HH24:MI:SS') + (date1 - date2), 'HH24:MI:SS') time_difference from ...

Note that this query only uses the time portion of the date and ignores the date itself. It will thus never return a value bigger than 23:59:59.

How does one add a day/hour/minute/second to a date value?

The SYSDATE pseudo-column shows the current system date and time. Adding 1 to SYSDATE will advance the date by 1 day. Use fractions to add hours, minutes or seconds to the date. Look at these examples: SQL> select sysdate, sysdate+1/24, sysdate +1/1440, sysdate + 1/86400 from dual;

SYSDATE SYSDATE+1/24 SYSDATE+1/1440 SYSDATE+1/86400 -------------------- -------------------- -------------------- -------------------- 03-Jul-2002 08:32:12 03-Jul-2002 09:32:12 03-Jul-2002 08:33:12 03-Jul-2002 08:32:13The following format is frequently used with Oracle Replication:

select sysdate NOW, sysdate+30/(24*60*60) NOW_PLUS_30_SECS from dual;

NOW NOW_PLUS_30_SECS -------------------- -------------------- 03-JUL-2002 16:47:23 03-JUL-2002 16:47:53

How does one count different data values in a column?

Use this simple query to count the number of data values in a column: select my_table_column, count(*)from my_tablegroup by my_table_column;

A more sophisticated example... select dept, sum( decode(sex,'M',1,0)) MALE, sum( decode(sex,'F',1,0)) FEMALE, count(decode(sex,'M',1,'F',1)) TOTAL from my_emp_table group by dept;

How does one count/sum RANGES of data values in a column?

A value x will be between values y and z if GREATEST(x, y) = LEAST(x, z). Look at this example: select f2, sum(decode(greatest(f1,59), least(f1,100), 1, 0)) "Range 60-100", sum(decode(greatest(f1,30), least(f1, 59), 1, 0)) "Range 30-59", sum(decode(greatest(f1, 0), least(f1, 29), 1, 0)) "Range 00-29" from my_table group by f2;For equal size ranges it might be easier to calculate it with DECODE(TRUNC(value/range), 0, rate_0, 1, rate_1, ...). Eg. select ename "Name", sal "Salary", decode( trunc(f2/1000, 0), 0, 0.0, 1, 0.1, 2, 0.2, 3, 0.31) "Tax rate" from my_table;

Can one retrieve only the Nth row from a table?

provided this solution to select the Nth row from a table: SELECT * FROM ( SELECT ENAME,ROWNUM RN FROM EMP WHERE ROWNUM < 101 ) WHERE RN = 100;

Note: Note: In this first it select only one more than the required row, then it selects the required one. Its far better than using MINUS operation.

provided this solution: SELECT f1 FROM t1 WHERE rowid = ( SELECT rowid FROM t1 WHERE rownum <= 10 MINUS SELECT rowid FROM t1 WHERE rownum < 10);Alternatively... SELECT * FROM emp WHERE rownum=1 AND rowid NOT IN (SELECT rowid FROM emp WHERE rownum < 10);Please note, there is no explicit row order in a relational database. However, this query is quite fun and may even help in the odd situation.

Can one retrieve only rows X to Y from a table?

provided this solution to the problem: SELECT * FROM ( SELECT ENAME,ROWNUM RN FROM EMP WHERE ROWNUM < 101 ) WHERE RN between 91 and 100 ;

Note: the 101 is just one greater than the maximum row of the required rows (means x= 90, y=100, so the inner values is y+1).

Another solution is to use the MINUS operation. For example, to display rows 5 to 7, construct a query like this: SELECT * FROM tableX WHERE rowid in ( SELECT rowid FROM tableX WHERE rownum <= 7 MINUS SELECT rowid FROM tableX WHERE rownum < 5);Please note, there is no explicit row order in a relational database. However, this query is quite fun and may even help in the odd situation.

How does one select EVERY Nth row from a table?

One can easily select all even, odd, or Nth rows from a table using SQL queries like this:

Method 1: Using a subquery SELECT * FROM emp WHERE (ROWID,0) IN (SELECT ROWID, MOD(ROWNUM,4) FROM emp);Method 2: Use dynamic views (available from Oracle7.2): SELECT * FROM ( SELECT rownum rn, empno, ename FROM emp ) temp

WHERE MOD(temp.ROWNUM,4) = 0;Please note, there is no explicit row order in a relational database. However, these queries are quite fun and may even help in the odd situation.

How does one select the TOP N rows from a table?

Form Oracle8i one can have an inner-query with an ORDER BY clause. Look at this example: SELECT * FROM (SELECT * FROM my_table ORDER BY col_name_1 DESC) WHERE ROWNUM < 10;Use this workaround with prior releases: SELECT * FROM my_table a WHERE 10 >= (SELECT COUNT(DISTINCT maxcol) FROM my_table b WHERE b.maxcol >= a.maxcol) ORDER BY maxcol DESC;

How does one code a tree-structured query?

Tree-structured queries are definitely non-relational (enough to kill Codd and make him roll in his grave). Also, this feature is not often found in other database offerings.

The SCOTT/TIGER database schema contains a table EMP with a self-referencing relation (EMPNO and MGR columns). This table is perfect for tesing and demonstrating tree-structured queries as the MGR column contains the employee number of the "current" employee's boss.

The LEVEL pseudo-column is an indication of how deep in the tree one is. Oracle can handle queries with a depth of up to 255 levels. Look at this example: select LEVEL, EMPNO, ENAME, MGR from EMP connect by prior EMPNO = MGR start with MGR is NULL;One can produce an indented report by using the level number to substring or lpad() a series of spaces, and concatenate that to the string. Look at this example: select lpad(' ', LEVEL * 2) || ENAME ........One uses the "start with" clause to specify the start of the tree. More than one record can match the starting condition. One disadvantage of having a "connect by prior" clause is that you cannot perform a join to other tables. The "connect by prior" clause is rarely implemented in the other database offerings. Trying to do this programmatically is difficult as one has to do the top level query first, then, for each of the records open a cursor to look for child nodes.

One way of working around this is to use PL/SQL, open the driving cursor with the "connect by prior" statement, and the select matching records from other tables on a row-by-row basis, inserting the results into a temporary table for later retrieval.

How does one code a matrix report in SQL?

Look at this example query with sample output: SELECT *

FROM (SELECT job, sum(decode(deptno,10,sal)) DEPT10, sum(decode(deptno,20,sal)) DEPT20, sum(decode(deptno,30,sal)) DEPT30, sum(decode(deptno,40,sal)) DEPT40 FROM scott.emp GROUP BY job) ORDER BY 1;

JOB DEPT10 DEPT20 DEPT30 DEPT40 --------- ---------- ---------- ---------- ---------- ANALYST 6000 CLERK 1300 1900 950 MANAGER 2450 2975 2850 PRESIDENT 5000 SALESMAN 5600

How does one implement IF-THEN-ELSE in a select statement?

The Oracle decode function acts like a procedural statement inside an SQL statement to return different values or columns based on the values of other columns in the select statement.

Some examples: select decode(sex, 'M', 'Male', 'F', 'Female', 'Unknown') from employees;

select a, b, decode( abs(a-b), a-b, 'a > b', 0, 'a = b', 'a < b') from tableX;

select decode( GREATEST(A,B), A, 'A is greater OR EQUAL than B', 'B is greater than A')...

select decode( GREATEST(A,B), A, decode(A, B, 'A NOT GREATER THAN B', 'A GREATER THAN B'), 'A NOT GREATER THAN B')...Note: The decode function is not ANSI SQL and is rarely implemented in other RDBMS offerings. It is one of the good things about Oracle, but use it sparingly if portability is required.

From Oracle 8i one can also use CASE statements in SQL. Look at this example: SELECT ename, CASE WHEN sal>1000 THEN 'Over paid' ELSE 'Under paid' END FROM emp;

How can one dump/ examine the exact content of a database column?

SELECT DUMP(col1) FROM tab1 WHERE cond1 = val1;

DUMP(COL1) Typ=96 Len=4: 65,66,67,32

Can one drop a column from a table?

From Oracle8i one can DROP a column from a table. Look at this sample script, demonstrating the ALTER TABLE table_name DROP COLUMN column_name; command.

Other workarounds: 1. SQL> update t1 set column_to_drop = NULL; SQL> rename t1 to t1_base; SQL> create view t1 as select <specific columns> from t1_base;

2. SQL> create table t2 as select <specific columns> from t1; SQL> drop table t1; SQL> rename t2 to t1;

Can one rename a column in a table?

No, this is listed as Enhancement Request 163519. Some workarounds: 1. -- Use a view with correct column names... rename t1 to t1_base; create view t1 <column list with new name> as select * from t1_base;

2. -- Recreate the table with correct column names... create table t2 <column list with new name> as select * from t1; drop table t1; rename t2 to t1;

3. -- Add a column with a new name and drop an old column... alter table t1 add ( newcolame datatype ); update t1 set newcolname=oldcolname; alter table t1 drop column oldcolname;

How can I change my Oracle password?

Issue the following SQL command: ALTER USER <username> IDENTIFIED BY <new_password>

From Oracle8 you can just type "password" from SQL*Plus, or if you need to change another user's password, type "password user_name".

How does one find the next value of a sequence?

Perform an "ALTER SEQUENCE ... NOCACHE" to unload the unused cached sequence numbers from the Oracle library cache. This way, no cached numbers will be lost. If you then select from the USER_SEQUENCES dictionary view, you will see the correct high water mark value that would be returned for the next NEXTVALL call. Afterwards, perform an "ALTER SEQUENCE ... CACHE" to restore caching.

You can use the above technique to prevent sequence number loss before a SHUTDOWN ABORT, or any other operation that would cause gaps in sequence values.

Workaround for snapshots on tables with LONG columns

You can use the SQL*Plus COPY command instead of snapshots if you need to copy LONG and LONG RAW variables from one location to another. Eg: COPY TO SCOTT/TIGER@REMOTE -CREATE IMAGE_TABLE USING - SELECT IMAGE_NO, IMAGE - FROM IMAGES;Note: If you run Oracle8, convert your LONGs to LOBs, as it can be replicated.