Oracle Demo File

7/29/2019 Oracle Demo File

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Oracle

Introduction to Oracle

The oracle corporation is the worlds leading supplier of software for

information management and worlds second largest independent software

company. Oracle is the top selling multi user RDBMS. Oracle application

covers business intelligence, ecommerce, financials, human resources,

manufacturing, mobile, project, and sales.

Features of Oracle

Client/Server Architecture

Large database and space management

Concurrent Processing

It is only meant for Demo of Practical file of MCA-2nd Year (3rd Semester) Students. Nobody will

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High transaction processing performance

High Availability

Controlled availability

Openness industry standards

Manageable security

Database enforced integrity

Distributed system

Portability

Compatibility

Replicated environment


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SQL

Introduction to SQL

SQL stands for Structured Query Language. SQL is a simple and powerful

language used to create access and manipulate data and structure in the

database. SQL is like plain English, which is easy to understand and to write.

The history of SQL begins in an IBM laboratory in San Jose, California, where

SQL was developed in the late 1970s. The initials stand for Structured Query

Language, and the language itself is often referred to as "sequel." It was

originally developed for IBM's DB2 product (a relational database management

system, or RDBMS, that can still be bought today for various platforms and

environments). In fact, SQL makes an RDBMS possible.

SQL is a nonprocedural language, in contrast to the

procedural or third-generation languages (3GLs) such as COBOL and C that

had been created up to that time. SQL is the de facto standard language used to


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manipulate and retrieve data from these relational databases. SQL enables a

programmer or database administrator to do the following:

Modify a database's structure

Change system security settings

Add user permissions on databases or tables

Query a database for information

Update the contents of a database


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Types of SQL statements

There are three types of SQL statements:-

1. Data Definition Language statements: - DDL statements are used to define,

alter or drop database objects. The following table gives an overview about

DDL statements.

Sr.No Need and Usages the SQL DDL statement

1. Create schema objects create

2. Alter schema objects alter

3. Delete schema objects delete

4. Rename schema objects rename

5. Grant and take away privileges grant, revoke

And rights

6. Add a comment to the data

Dictionary comment


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2. Data Manipulation Language statements: - Once the tables have been

created, the DML statements enable users to query or manipulate data in

existing schemas objects. DML statements are normally the most frequently

used commands. The following table gives an overview about DML statements:

Sr.No Need and Usages The SQL DML statement

1. Remove rows from tables or delete

Views

2. Add new rows of data into insert

Table or view

3. Retrieve data from one or more select

Tables

4 Change column values in existing update

Rows of a table or view


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3. Transaction Control Language statements: - TCL statements manage the

Changes made by DML statements and group DML statements into transaction.

The Following table gives an overview about TCL

Sr.No Need and Usages The SQL TCL statement

1. Make a transaction changes commit

Permanent

2. Undo changes in a transaction rollback

Either since the transaction started

Or since a savepoint

3. Set point to which transaction can be savepoint

Rolled back

4. Establish properties for a transaction set transaction


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Data Types

The information in a database is maintained in the form of table and each table

consist of rows and columns, which store data and therefore this data must have

some data type i.e. the type of data, which is stored in a table. The different data

types available in oracle are:

Data Types Description

Vachar2 Contains variable length text string of up to

2000 bytes

Char Contains fixed text strings of up to 255

bytes

Number Contains numeric dataDate Contains date data

Raw Contains binary data up to 255 bytes

Long Contains text data of up to 2gigabytes


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Rules for SQL

SQL statements may be on one or many lines.

Command words cannot be split across lines.

A; is used to end of SQL statements.

Identifier can contain up to 30 characters and must start with an alphabetic

character.


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The basic Select statements

The SELECT statement is the most commonly used statement in SQL and it is

used to retrieve information already stored in the database. To retrieve data you

can either select all the column values or name specific columns in the

SELECT clause to retrieve data.

Selecting all columns

Selecting specific columns


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Using arithmetic operators

Oracle allows arithmetic operators to be used while viewing records from a

table or while performing data manipulation operations such as insert, update

and delete. These are:-

1. + Addition

2. - Subtraction

3. / Division

4. * Multiplication

5. ** Exponentiation

6. ( ) Enclosed operation


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Using column aliases

Column aliases are used to rename column headings.

Using concatenation operator


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We can link columns to other columns, arithmetic expressions, or constant

values to create a character expression by using the concatenation operator.


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Eliminating duplicate rows

To eliminate duplicate rows in the result, include the distinct keyword in the

select clause immediately after the select keyword

Limiting rows using a selection

You can restrict the rows returned from the query by using the where clause. A

where clause contains a condition that must be met, and it directly follows the

from clause. If the condition is true the row meeting the condition is returned.


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Using Between operator

In order to select data that is within a range of values, the BETWEEN operator

is used. The BETWEEN operator allows the selection of rows that contain

values within specific lower and upper limit. The range coded after the word

BETWEEN is inclusive. The owner value must be coded first. The two values n

between the range must be linked with the keyword AND. A BETWEEN

operator can be used with both character and numeric data types. However one

cannot mix the data type i.e. the lower value of a range of values from character

column and the other from numeric column.

Using the IN condition


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Pattern Matching

The character pattern-matching operation is referred to as a wildcard search.

You can select rows that match a character pattern using the like condition. The

character pattern matching operation is referred to as a wildcard search. Two

symbols can be used to construct the search string.

% Represents any sequence of zero or more characters.

_ Represents any single character


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Using the NULL condition

The null condition includes the is null condition and the is not null condition.

The is null condition tests for nulls. A null value means the value is

unavailable, unassigned, unknown or inapplicable. Therefore, you can not test

with = because a null cannot be equal or unequal to any value.


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Using the logical operators

Using the AND operator: -Returns true if both component conditions are true.

Using the OR operator: -Returns true if either component condition is true.


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Sorting rows

The order of rows returned in a query is undefined. The order by clause can be

used to sort the rows. If you use the order by clause it must be the last clause of

the sql statement. You can specify an expression, or an alias or column position

as the sort condition.

In ascending order

In descending order


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Joining two tables

When data from more than one table in the database is required, a join

condition is used. Rows in one table can be joined to rows in another table

according to common values existing in corresponding columns, that is, usually

primary and foreign key columns. To display data from two or more related

tables, write a simple join condition in the WHERE clause.

In the syntax:

Table1.column denotes the table and column from which data is retrieved


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Table1.column1= is the condition that join the tables together

Table2.column2


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Using group functions

Group functions operate on set of rows to give one result per set.

MAX Function

MIN Function

COUNT Function


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Using AVG Function

Using SUM Function


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The Having clause

You use the having clause to specify which groups are to be displayed, and

thus, you further restrict the groups on the basic of aggregate information.

In the syntax:

Group condition: - restricts the groups of rows returned to those groups for

which the specified condition is true

The Oracle server performs the following steps when you use the HAVING

clause:

1. Rows are grouped.

2. The group function is applied to the group.

3. The groups that match the criteria in the HAVING clause are displayed.


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Using Sub queries

A sub query is a select statement that is embedded in a clause of another select

statement. You can build powerful statement out of simple ones by using sub

queries. They can be very useful when you need to select rows from a table

with a condition that depends on the data in the table itself.

You can place the sub query in a number of SQL clauses

1. The WHERE clause

2. The HAVING clause

3. The FROM clause

In the syntax

Operator includes a comparison condition such as >, =, or IN


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Creating and managing tables

Create tables to store data by executing the SQL create table statement. To

create a table a user must have create table privilege and a storage area in which

to create objects.

Creating table

Confirming table creation

Creating a table using a sub query


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Alter Table statement

After we create a table, we may need to change the table structure because; you

omitted a column, your column definitions need to be changed, or you need to

remove columns. You can do this by using the alter table statement.

Adding a column

Modifying a column


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Dropping Tables

The drop table statement removes the definition of an oracle table. When you

drop a table, the database loses all the data in the table and all the indexes

associated with it.

All data is deleted from the table.

Any views and synonyms remains but are invalid.

Any pending transactions are committed

.


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Inserting data into a table

You can add new rows to a table by issuing the insert statement. Because you

can insert a new row that contains values for each column, the column list is not

required in the insert clause. However if you do not use the column list the

values must be listed according to the default order of the columns in the table

and a value must be provided for each column.

Specifying data for all columns

Specifying data for selected columns


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Updating data

We can modify existing rows by using the update statement. The update

statement modifies specific rows if the where clause is specified.


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Deleting rows

We can remove existing rows by using the delete statement. We can delete

specific rows by using the where clause in the delete statement.


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Primary key: - A primary key constraint creates a primary key for the table. Only

one primary key can be created for each table. The primary key constraint is a

column that uniquely identifies each row in a table. A primary key column can not

contain a null value.

Foreign key: - The foreign key constraint designates a column as a foreign key and

establishes a relationship between a primary key or a unique key in the same table or

a different table.


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Check: - Defines a condition that each row must satisfy


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Views

A view is a virtual or logical table that allows the viewing or manipulating the

contents of one or more tables. Views do not really contain or store data, but

they take data from the tables on which they are based, called base tables.


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Sequences

Oracle provides an object called a sequence that can generate unique numeric

value. If the value entered in a column is computer generated it will always

fulfill the unique constraint and the row will always be accepted for storage.


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PL/SQL

Introduction to PL/SQL

PL/SQL is a procedure language that oracle developed as an extension to

standard SQL in order to provide a way to execute procedure logic on the

database. PL/SQL provide a mechanism for developer to add a procedure

component at the server level PL/SQL is block structure language A PL/SQL

block is a syntactically unit that might contain programmer code , variable

declaration , error handler , procedure , function and even other PL/SQL block

Syntax for PL/SQL block:

Declare

Variable_declarations

Begin

Program_code


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End;

In this syntax variable declaration are any variable that might want to define

cursor definition and nested PL/SQL procedure and function are also define

here program code refer to the PL/SQL statement that make up the block.


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Advantage of PL/ SQL

1. PL/SQL is a development tool that only not supports SQL data

manipulation but also provides facility of conditional checking, branching

and looping.

2. PL/SQL sends an entire block of SQL statement to the oracle engine all in

one go. Communication between the program block and oracle engine

reduces considerably, reduces network traffic since the oracle engine got

the SQL statement as a single block. It processes this code much faster

than if it got once as one sentence at a time

3. PL/SQL also permits dealing with error as required and facilitates

displaying user friendly message when errors are encountered

4. Via PL/SQL all sort of calculation can be done quickly and efficiently

without the use oracle engine. This considerably improve transaction

performance

5. Applications written in PL/SQL are portable to any computer, hardware

and operating system where as oracle is operational.


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Programs

Program to calculate sum of two numbers

Program to find greater of two numbers


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Program to find factorial of a given number


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Program to print Fibonacci series


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Procedures and Functions

A procedure or function is a logically grouped set of SQL and PL statement that

performs a specific task. A procedure and function is a named PL/SQL ode

block that has been complied and stored in one of the oracle engine system

table .procedure and function are made up of three parts : -

1. Declarative part

2. Executable part

3. An optional exception handling part


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Functions

Using local function

Using stored function


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Cursors

The oracle engine uses a work area for its internal processing in order to

execute an SQL statement this work area is private to SQL operation and is

called cursor

Types of cursors

Implicit cursor: - The oracle engine implicitly opens a cursor on the server to

process each SQL statement. Since the implicit cursor is opened and managed

by oracle server internally the function of reversing an area in memory,

populating this area with appropriate data, processing the data in memory area,

releasing the memory area when the processing is complete is taken care of by

the oracle engine

Explicit cursor: - When individual record in a table have to a process inside a

PL/SQL block a cursor is used this cursor will be declared and mapped to an

SQL query in declare section of the PLSQL block and used within its


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executable section. A cursor thus created and used is known as an explicit

cursor


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Program to demonstrate implicit cursors

Explicit cursor management

This step involved in using an explicit cursor and manipulating data

1. Declare a cursor mapped to a SQL select statement that retrieves data for

processing

2. Open the cursor

3. Fetch data from the cursor one row at a time into memory variables


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4. Process the data held in the memory variables as required using a loop

5. Exit from the loop after processing is complete

6. Close the cursor

Program to demonstrate implicit cursors


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Triggers

Database trigger are data base object that are stored on the server. The oracle

engine allows the definition of procedure that are implicitly executed when an

insert, update or delete is issued against the table these procedure are called

database trigger These data base object consist of the following distinct section

1. A named data base event

2. A PL/SQL block that executes when the event occurs


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Packages

A package is an oracle object, which holds other objects with in it. Objects

commonly held with in a package are procedures, functions, variables,

constants, cursors and exception handlers. Package can contain PL/SQL block

of code, which has been written to perform some process. PLSQL block of

code do not require any kind of input from other PLSQL block of code. A

package has two components. A specification and a body. A package

specification declares the types, memory variables, constants, exceptions,

cursors and sub programs that are available for use. A package body fully

defines cursors, functions, procedures and thus implements the specification

Creating package specification


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Creating package body

Using packages


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