SQL in Oracle Jan. 2008Yangjun Chen ACS-39021 Outline: SQL in Oracle Oracle database system...

Jan. 2008 Yangjun Chen ACS-3902 1

SQL in Oracle

Outline: SQL in Oracle

•Oracle database system architecture

- Oracle server

- Oracle client

•SQL*Plus

•PL/SQL


SQL in Oracle

Oracle system architecture

•Oracle server and Oracle client

Oracle server

Oracle client Oracle client Oracle client

data managementtransaction controlrecoverysecurity

interface to manipulate datatools to support development of application


SQL in Oracle

SQL*Plus

• Interface to manipulate Oracle databases

• Tool to support the development of application

- SQL*Plus as an interface

To start SQL*Plus, enter Oracle username and password:

$> sqlplus jason/athena

(from a command line operating system such UNIX)

or

click: Start Program Oracle

(for Windows - SQL*Plus)


SQL in Oracle


Create a table with integrity constraints

CREATE TABLE bank_account

(bank_acct_no VARCHAR2(40),

empid NUMBER(10),

BANK_ROUTE_NO VARCHAR2(40),

BANK_NAME VARCHAR2(50),

CONSTRAINT pk_bank_acct_01,

PRIMARY KEY (bank_acct_no),

CONSTRAINT fk_bank_acct_01

FOREIGN KEY (empid) REFERENCE employee (empid));


SQL in Oracle


Create a table with integrity constraints

CREATE TABLE bank_account

(bank_acct_no VARCHAR2(40),

empid NUMBER(10),

BANK_ROUTE_NO VARCHAR2(40),

BANK_NAME VARCHAR2(50),

CONSTRAINT pk_bank_acct_01,

PRIMARY KEY (bank_acct_no),

CONSTRAINT fk_bank_acct_01

FOREIGN KEY (empid) REFERENCE employee (empid)

ON DELETE CASCADE);


SQL in Oracle

CREATE TABLE employee

(empid NUMBER(10),

lastname VARCHAR2(25),

firstname VARCHAR2(25),

salary NUMBER(10, 4),

home_phone NUMBER(15),

CONSTRAINT pk_employee_01

PRIMARY KEY (empid),

CONSTRAINT uk_employee_01

UNIQUE (home_phone));

The difference between PRIMARY KEY and UNIQUE isthat for a UNIQUE attribute NULL value is allowed.


SQL in Oracle


NOT NULL constraints and check constraints

CREATE TABLE employee

(empid NUMBER(10),

lastname VARCHAR2(25), NOT NULL

firstname VARCHAR2(25), NOT NULL

salary NUMBER(10, 4), CHECK(salary < 50000

home_phone NUMBER(15),

CONSTRAINT pk_employee_01

PRIMARY KEY (empid),

CONSTRAINT uk_employee_01

UNIQUE (home_phone));


SQL in Oracle


Adding and modifying columns

ALTER TABLE products

ADD (color VARCHAR2(10));


MODIFY (SERIAL# VARCHAR2(25));

Assume that SERIAL# is an attribute in PRODUCTS with

type VARCHAR2(10).


SQL in Oracle


Modifying integrity constraints

ALTER TABLE productsMODIFY (color NOT NULL);

ALTER TABLE productsADD (CONSTRAINT pk_products_01 PRIMARY KEY

(product#));

ALTER TABLE productsADD (CONSTRAINT fk_products_01 FOREIGN KEY

REFERENCES (AVAIL_COLOR.color));


SQL in Oracle


Modifying integrity constraints

ALTER TABLE productsADD (UNIQUE (serial#));

ALTER TABLE productsADD (size CHECK

(size in ‘P’, “S’, ‘M’, ‘L’, ‘XL’, ‘XXL’, ‘XXXL));


SQL in Oracle


Enabling or disabling constraints

ALTER TABLE productsENABLE CONSTRAINT pk_products_01;

ALTER TABLE productsENABLE CONSTRAINT uk_products_03;


SQL in Oracle


Enabling or disabling constraints

ALTER TABLE productsDISABLE PRIMARY KEY;

ALTER TABLE productsDISABLE UNIQUE (serial#);

ALTER TABLE productsDISABLE PRIMARY KEY CASCADE;


SQL in Oracle


Dropping constraints

ALTER TABLE productsDROP CONSTRAINT uk_products_01;

ALTER TABLE productsDROP PRIMARY KEY CASCADE;


SQL in Oracle


Dropping Tables


ALTER TABLE productsDROP CONSTRAINT;

Truncating Tables

TRUNCATE TABLE products


SQL in Oracle


Changing Names of Objects

RENAME products TO objects

CREATE SYNONYM objects FOR products;CREATE PUBLIC SYNONYM objects FOR products;


SQL in Oracle


Sequences

A sequence is a special database object that generates integers according to specified rules at the time the sequence was created.

- In some cases, the primary key is not important to use for accessing data to store stored in a table.

Example: A doctor’s office may have a client tracking system that assigns each new patient a unique integer ID to identify their records.

- Using a sequence to generate primary keys automatically.


SQL in Oracle


Creating sequences

CREATE SEQUENCE countdown_20

START WITH 20

INCREMENT BY 1

NOMAXVALUE

CYCLE

ORDER;

CREATE SEQUENCE SOME_NUM

MINVALUE 0

MAXVALUE 1000

NOCYCLE

2019

...

12019...

01

...

1000


SQL in Oracle


Using sequences

SELECTsome_num.currval CURRENT

some_num.nextval NEXT

some_num.currval CURRENT

FROM dual

CURRENT NEXT CURRENT

1 2 2


SQL in Oracle


Using sequences

INSERT INTO expense(expense_no, empid, amt, submit_date)

VALUE(some_num.nextval, 59495, 456.34, ‘21-nov-99’);

UPDATE productSET product_num = some_num.currvalWHERE serial_num = 3498583945;


SQL in Oracle


Modifying a sequence definition

ALTER SEQUENCE countdown_20

INCREMENT BY 4;

ALTER SEQUENCE countdown_20

NOCYCLE;

ALTER SEQUENCE some_num

MAXVALUE 10000;


SQL in Oracle


Removing sequence

DROP SEQUENCE some_num;


SQL in Oracle


Views

Creating simple views

CREATE VIEW employee_view

AS (SELECT empid, lastname, firstname, salary

FROM employee

WHERE empid = 59495)

UPDATE employee_view

SET salary = 99000

WHERE empid = 59495


SQL in Oracle


Creating complex views


AS (SELECT e.empid empid, e.lastname lastname, e.firstname, firstname, e.salary salary, a.address, a.city, a.state, a.zipcode

FROM employee e, employee_address a

WHERE e.empid = a.empid)



FROM employee

WHERE empid = 59495)

WITH CHECK OPTION;


SQL in Oracle


Modifying views

CREATE OR REPLACE VIEW employee_view


FROM employee

WHERE empid = user)

WITH CHECK OPTION;

Removing views

DROP VIEW employee_view;


SQL in Oracle


Creating indexes manually

CREATE UNIQUE INDEX employee_lastname_index_01

ON employee (lastname);

CREATE INDEX employee_lastname_index_01

ON employee (lastname);

unique index

nonunique indexindexed columncontaons null value


SQL in Oracle


Creating indexes manually

CREATE UNIQUE INDEX employee_last_first_index_01

ON employee (lastname, firstname);

unique indexon the combinationof two columns:lastname, firstname


SQL in Oracle


Automatic indexes

Oracle will create a B-tree for an attrubute with ‘primary key’

constraint or ‘unique’ constraint.


SQL in Oracle

PL/SQL

• PL/SQL is a special language available for developers to code stored procedures that seamlessly integrate with database objects access via the language of database objects, SQL.

• PL/SQL procedure: a series of statements accepting and/or returning zero or more variables.

• PL/SQL function: a series of statements accepting zero or more variables and returning one value.

A PL/SQL procedure or a PL/SQL function is called a PL/SQL block.


SQL in Oracle

- PL/SQL

A PL/SQL block normally contains three components:

•variable declaration section,

•executable section, and

•exception section.


SQL in Oracle

- PL/SQL

There are two kinds of blocks in Oracle: named and unnamed or anonymous blocks.

Named block

CREATE FUNCTION convert_money (AMOUNT IN NUMBER,convert_currency IN VARCHAR2,old_currency IN VARCHAR2) ISmy_new_amt number(10) := 0;bad_data exception;

BEGINIF my_new_amt > 3 THEN ...ELSE ...END IF;

Decralation section

Executable section


SQL in Oracle

- PL/SQL

...

EXCEPTION

WHEN bad_data THENDBMS_OUTPUT.PUT_LINE(‘Error condition’);

END;

Exception handler


SQL in Oracle

- PL/SQL

Unnamed block

DECLAREmy_new_amt number(10) := 0;bad_data exception;

BEGINIF my_new_amt > 3 THEN ...ELSE ...END IF;

EXCEPTION

WHEN bad_data THENDBMS_OUTPUT.PUT_LINE(‘Error condition’);

END;


SQL in Oracle

• Datatypes used in PL/SQL

There are two kinds of datatypes: database datatypes and nondatabase types.

Database datatypes

There are several datatypes that can be used in PL/SQL that correspond to the datatypes used on the database, i.e., the datatypes used for defining a table.

1. NUMBER(size[,precision]) - used to any number.

NUMBER(10), NUMBER(10, 5)

2. CHAR(size), VARCHAR(size) - used to store alphanumeric text strings. The CHAR datatype pads the value stored to the full length of the variable with blanks.


SQL in Oracle

3. DATE - Used to store dates.

4. LONG - Stores large blocks of text, up to 2 gigabytes in length.

5. LONG RAW - Stores large blocks of data stored in binary format. RAW - Stores smaller blocks of data stored in binary format.

6. BLOB, CLOB, NCLOB BFILE - Large object datatype.


SQL in Oracle

Nondatabase datatypes

1. DEC, DECIMAL, REAL, DOUBLE_PRECISION - These numeric datatypes are a subset of the NUMBER datatype that is used for variable declaration in PL/SQL.

2. INTEGER, INT, SMALLINT, NATURAL, POSITIVE, NUMERIC - These numeric datatypes are a subset of the NUMBER datatype that is used for variable declaration in PL/SQL.

3. BINARY_INTEGER, PLS_INTEGER - These datatypes store integers. A variable in either format cannot be stored in the database without conversion first.


SQL in Oracle

4. CHARACTER - Another name for the CHAR datatype.

5. VARCHAR - Another name for the VARCHAR2 datatype.

6. BOOLEAN - Stores a TRUE/FALSE value.

7. TABLE/RECORD - Tables can be used to store the equivalent of an array, while records store variables with composite datatypes.


SQL in Oracle

%TYPE

•Using the %TYPE keyword, you can declare a variable to be of the type same as an attribute.

DECLARE

my_employee_id employee.empid%TYPE

BEGIN ...

DECLARE

my_salary employee.salary%TYPE := 0;

my_lastname employee.lastname%TYPE := ‘SMITH’;

BEGIN ...


SQL in Oracle

%ROWTYPE

•Using the %ROWTYPE keyword, you can declare a variable to be of the type same as a table.

DECLARE

my_employee employee%ROWTYPE

BEGIN ...


SQL in Oracle

DECLARE

TYPE t_employee IS RECORD (

my_empid employee.empid%TYPE,

my_lastname employee.lastname%TYPE,

my_firstname employee.firstname%TYPE,

my_salary employee.firstname%TYPE);

my_employee t_employee;

BEGIN ...


SQL in Oracle

Constant declaration

CREATE FUNCTION find_circle_area (

p_radius IN circle.radius%TYPE

RETURN NUMBER IS

my_area number(10) := 0;

pi constant number(15, 14) := 3.14159265358;

BEGIN

my_area := (p_radius*p_radius)*pi;

Return (my_area);

END;


SQL in Oracle

Using SQL Statements in PL/SQL

DECLAREmy_employee employee%ROWTYPE;my_lastname VARCHAR(30) := ‘SAMSON’;my_firstname VARCHAR(30) := ‘DELILAN’;my_salary NUMBER(10) := 49500;

BEGINSELECT *INTO my_employeeFROM employeeWHERE empid = 49594;

UPDATE employee

SET salary = my_employee.salary + 10000

WHERE empid = my_employee.empid;


SQL in Oracle

INSERT INTO employee (empid, lastname, firstname, salary)

VALUE (emp_sequence.nextval, my_lastname, my_firstname, my_salary);

my_employee.empid := 59495;

DELETE FROM employee

WHERE empid = my_empid;

END;


SQL in Oracle

CURSOR concept

•A cursor is an address in memory where a SQL statement is processed.

•There are two kinds of cursors: explicit and implicit

An explicit cursor is named address (via a variable)

An implicit cursor is unnamed address.


SQL in Oracle

CURSOR concept

•Explicit cursor - an named address where an SQL statement is processed.

DECLARE

high_pctinc constant number(10, 5) := 1.20;

med_pctinc constant number(10, 5) := 1.10;

low_pctinc constant number(10, 5) := 1.05;

my_salary employee.salary%TYPE;

my_empid employee.empid%TYPE;

CURSOR employee_crsr IS

SELECT empid, salary

FROM employee;


SQL in Oracle

BEGIN

OPEN employee_crsr;

LOOP

FETCH employee_crsr INTO my_empid, my_salary;

EXIT WHEN employee_crsr%NOTFOUND;

IF my_empid = 59697 OR my_empid = 76095 THEN

UPDATE employee SET salary = my_salary*high_pctinc



SQL in Oracle

ELSEIF my_empid = 39294 OR my_empid = 94329 THEN

UPDATE employee SET salary = my_salary*low_pctinc


ELSE

UPDATE employee SET salary = my_salary *mid_pctinc


END IF;

END LOOP;

END;


SQL in Oracle

CURSOR concept

•Implicit cursor - an unnamed address where an SQL statement is processed. Therefore, there is no declaration for an implicit cursor variable.

Whenever an SQL is evaluated, an implicit cursor is automatically associated with it.

Such an implicit cursor can be manipulated using the cursor attributes:

%notfound

%found

%rowcount

%isopen


SQL in Oracle

•Implicit cursor DECLARE

my_empid employee.empid%TYPE := 59694;

my_salary employee.salary%TYPE := 99000;

my_lastname employee.lastname%TYPE := ‘RIDDINGS’;

BEGIN

UPDATE employee

SET salary = my_salary

WHERE = my_empid;

IF sql%NOTFOUND THEN

INSERT INTO EMPLOYEE (empid, lastname, salary)

VALUE(my_empid, my_lastname, my_salary);

END IF;

END;


SQL in Oracle

•Parameters and explicit cursors

DECLARE

high_pctincconstantnumber(10, 5) := 1.20;

med_pctincconstantnumber(10, 5) := 1.10;

low_pctinc constantnumber(10, 5) := 1.05;

my_salary employee.salary%TYPE;

my_empid employee.empid%TYPE;

CURSOR employee_crsr (low_end in VARCHAR2, high_end in VARCHAR2) IS

SELECT empid, salary

FROM employee;

WHERE UPPER(substr(lastname, 1, 1) BETWEEN UPPER(low_end)

AND UPPER(high_end)


SQL in OracleBEGIN

OPEN employee_crsr(‘A’, ‘M’);

LOOP

FETCH employee_crsr INTO my_empid, my_salary;

EXIT WHEN employee_crsr%NOTFOUND;

IF my_empid = 59697 OR my_empid = 76095 THEN

UPDATE employee SET salary = my_salary*high_pctinc


ELSEIF my_empid = 39294 OR my_empid = 94329 THEN

UPDATE employee SET salary = my_salary*low_pctinc


ELSE

UPDATE employee SET salary = my_salary *mid_pctinc


END IF;

END LOOP;

END;


SQL in Oracle

- Error handling

•In Oracle PL/SQL, there are three types of exceptions:

predefined exceptions,

user-defined exceptions, and

internal exceptions.

Predefined exceptions

Oracle has designed several ‘built-in’ exceptions used to handle common situations that may occur on the database.

Example: statement returns no data.

When a statement expecting one piece of data receives more than one piece of data.


SQL in Oracle

- Error handling

Predefined exceptions

Some of the predefined cursors are represented using the following key words:

invalid_cursor - Occurs when an attempt is made to close a nonopend cursor.

cursor_already_open - Occurs when an attempt is made to open a nonclosed cursor.

dup_val_on_index - Unique or primary-key constraint violation.

No_data_found - No rows were selected or changed by the SQL operation.


SQL in Oracle

too_many_rows - More than one row was obtained by a single-row subsequently, or in another SQL statement operation where Oracle was expecting one row.

zero_divide - An attempt was made to divide by zero.

rowtype_mismatch - The datatypes of the record to which data from the cursor is assigned are incompatible.

Invalid_number - An alphanumeric string was referenced as a number.

EXCEPTIONWHEN NO_DATA_FOUND THEN

DBMS_OUTPUT.PUT_LINE(‘No data is found’);END


SQL in Oracle

- Error handling

User-defined exceptions

In addition to predefined exceptions, there can be created a whole host of user-defined exceptions that handle situations that may arise in the code.

To handle exceptions, a PL/SQL code should contain:

exception declaration,

exception testing, and

exception handling.


SQL in Oracle

- Error handling

User-defined exceptions

DECLAREmy_empid employee.empid%TYPE := 59694;

my_emp_record employee%ROWTYPE := 99000;

my_salary_null EXCEPTION;

BEGIN

SELECT * FROM employee

INTO my_emp_record


IF my_emp_record.salary IS NULL THEN

RAISE my_salary_null;

END IF;


SQL in Oracle

EXCEPTION

WHEN NO_DATA_FOUND THEN

DBMS_OUTPUT.PUT_LINE(‘No data is found’);

WHEN my_salary_null THEN

DBMS_OUTPUT.PUT_LINE(‘Salary column was null for employees’);

END;


SQL in Oracle

- Error handling

Internal exceptions

•All the Oracle errors are represented by alphanumeric string of the form: ORA-xxxx.

Example: ORA-1400.

•A predefined exception is an association of a name with an Oracle alphanumeric string representing an error.

•One can extend the list of predefined exceptions by associating a new name with an Oracle alphanumeric string representing an error, using pragam exception_init keywords.


SQL in Oracle

DECLARE

my_emp_record employee%ROWTYPE;

salary_null exception;

pragam exception_init (salary_null, -1400);

BEGIN

my_emp_record.empid := 59485;

my_emp_record.lastname := ‘RICHARD’;

my_emp_record.firstname := ‘JEAN-MARIE’;

my_emp_record.salary := 65000;

INSERT INTO employee(empid, lastname, firstname, salary)

VALUE(my_emp_record.empid, my_emp_record.lastname,

my_emp_record.firstname, my_emp_record.salary);


SQL in Oracle

EXCEPTION

WHEN NO_DATA_FOUND THEN

DBMS_OUTPUT.PUT_LINE(‘No data is found’);

WHEN salary_null THEN

DBMS_OUTPUT.PUT_LINE(‘Salary column was null for employees’);

END;

SQL in Oracle Jan. 2008Yangjun Chen ACS-39021 Outline: SQL in Oracle Oracle database system...

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