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Data definition language

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Create table command

It is used to define a new table

Each column definition of a table has three

parts:1. A name

2. Data type

3. size

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syntax

Create table table_name(column1

datatype(size),column2

datatype(size), columnN

datatype(size));

Example:

Create table student(roll_no number(10),

name varchar(20), city varchar (20));

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How to display a table

If we want to display the information about

the columns defined in a table then we use

following syntax:

describe table-name;

Example:

describe student

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output

Name Null? type

Roll_no Number(10)

Name Varchar(20)

DOB date

City Varchar(20)

State Varchar(20)

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Constraints in create table command

1. Primary key constraint

2. Unique constraint

3. Not-null constraint4. Foreign key constraint

5. Check constraint

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Primary key constraint

Primary key is applied to column so that this

column can be used to uniquely identify each

row in a table

A table have only one primary key

Primary key has following features:

1. Prima

ry key does not allow duplicate values

2. It does not allow null values

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syntax

Column_name datatype(size) Primary Key

Example:

create table student(Roll_no number(10) Primary Key,

name var

char

(20) , city var

char

(20))OR

Create table student(Roll_No number(10) , Namevarchar(20) , City varchar(20) , Primary Key(Roll_No));

OR

Create table student(Roll_NO number(10) , Namevarchar(20) city varchar(20) , Constraint PK PrimaryKey(roll_no));

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Unique constraint

The unique constraint is used for the

candidate key columns so that they contain

the unique values for different entities.

Unique constraint will not allow the duplicate

values in the column to which they are

attached

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Characteristics of unique key

No allow duplicate values

Can accept null values

A table can have more than one unique key

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syntax

Column_name datatype(size) Unique

Example

create table student( reg_no char(10) PrimaryKey , roll_no number(10) Unique , student_ID

char(10) Unique , city varchar(20));

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Not null constraint

It ensures that the table column will not left

empty

Syntax:column name datatype(size) Not Null

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Foreign key constraint

The table in which foreign key is defined is

called foreign table or detail table

and the table whose prima

ry key is

refe

renced

by the foreign table is known as Master table

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characteristics

It contain only those values that are present inthe primary key of master tabel

Value in the foreign key can be null or duplicate

values In foreign key if we insert a value which is not

present in the primary key the oracle engine willreject the data

A record in a master table cannot be deleted ifthe corresponding record in the foreign tableexist

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syntax

column-name datatype(size)

References

Master-Table-name(column-name)

Example:create table department( department_id char(10)

Primary Key , department_name varchar(10));

after creating the master table foreign table is created

as:Create table course (course_id char(10) Primary Key,

Dept_id varchar (20) Refrences department(dept_id));

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Check constraint

Used to specify the data validation for a column

Check constraint is a Boolean expression that is

evaluated to either True or False

Before inserting a value into the column (to which

check constraint is attached ) oracle engine

evaluates the Boolean condition

If the condition evaluated is true then databaseaccepts the value othervise it do not accept the

value

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syntax

column-name datatype(size) Check (BooleanExpression)

Example :

suppose that in employee table the age ofemployee must be between 22 and 30

syntax:

create table Employee(emp_id char(10)Primary key , ename varchar (20), age number(10) check (age BETWEEN 22 and 30));

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Alter table command

It is used to modify the structure of table

which is already existing

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Adding new column to an existing

table

syntax:

Alter table table-name ADD(col-name1

datatype(size), column-name2datatype(size),.column-nameN

datatype(size);

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Modifying an existing table

Used to increase or decrease the column

width and to change the datatype

syntax:Alter table table-name MODIFY (column-name

New-datatype(New Size));

Example:Alter table Employee Modify(emp_id

varchar(20));

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To add primary key

Alter table table-name ADD Primary Key

(column-name);

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Dropping the constraints

To remove primary :

Alter table table-name DROP constraint-name

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Dropping column from table

Alter table table-name DROP column

column-name;

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Drop table command

DROP table table-name

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Rename command

Use to change the name of existing table

Syntax:

Rename table-name TO New-table-name;

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Data manipulation language

Used to access or manipulate the data values

in the tables

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Insert command

Used to insert data rows in a table

We can either insert a row at a time or by

inser

ting the datar

ows fr

om alr

eady existingtable

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syntax

Insert into table-name (col-name1, col-

nameN)values(value1,...,valueN);

The number of values that appear in the

parenthesis after the keyword values must

match the number of columns in the list

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example

Insert into Emp( emp_id , name , dept_name ,

age , city , state)

values(E1 , raj , mech , 26 , pune , MH);

column name is optional

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For inserting data rows from another

table

Insert into table-name1

select col-name1,, col-nameN

From table-name2WHERE condition;

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UPDATE COMMAND

Use to modify already existing data values

It is use to update either

1. All ther

ows fr

om a table2. A selected set ofrows from a table

SYNTAX:

Update table-name

SET

col-name1 = value1,., col-nameN= valueN

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example

Change the city of each employee to

Chandigarh

Update EmpSET

City = Chandigarh;

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Syntax for updating selected rows

Update table-name

SET

Col-name1 = value1,., col-nameN = valueN

WHERE condition;Example:

Update Emp

SET

Age = 34

Where ename =sunil ;

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DELETE COMMAND

It is used to delete

1. All the rows from a table

2. A selected rows from a table

Syntax for deleting all the rows

Delete from table-name;

for deleting specific rows

Delete from Table-name

Where codition;

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select

Use to view orretrieve the rows from one or

more tables

Syntax:

Select C1,C2.., Cn

From R1,R2,..,RnWhere P;

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Use of select command

To access all the rows and all the columns

To access specific row and all the columns

To access specific columns and all the rows To access specific row and specific column

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To access all the rows and all the

columns

Select * from table_name;

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To access specific columns

select column-list

from table_name;

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To access specific rows

select * from table_name

When condition;

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To access specific rows and specific

columns

select column-listfrom table_name

where condition

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Select command with distinct clause

select DISTINCT column-nameFrom table- name;

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Select command with order by clause

select * from table-nameOrder By column-name Sort-order;

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Select command with arithmetic

operator

select column_name arithmetic operationfrom table-name

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Alias with select command

Alias is used to rename the column while

displaying the data . But the actual column

name in the structure does not change

SYNTAX:

select column-name, alias-name

from table name;

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Select command with between

operator

select * from table-nameWhere column-name BETWEEN LL AND UL;

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Select command with like operator

To match the string patterns

LIKE operator use two wild card character

1. Percent(%) to match any string of any length2. Underscore(_) to match a single character

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example

1. St% matches with any string starting with St

2. %y matches with any string ends with y

3. Mo_ _ _matches with any string started with

Mo and has three letters after it4. _ _ _ _ _a matches with any string ending with

a and has 5 letters before

5. _ _ _ _ matches any four characters

6. _ _% matches any string which is atleast twocharacters

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Cont..

select * from table_name

Where column-name LIKE R%;

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Select stmt with SET operation

Union

Syntax:

Select-statement1UNION

Select-statement2;

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intersect

Select statement 1

INTERSECT

Select- statement 2

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Select command with dual table

It is a small work-table

It consist of only one row and one column

The column name is Dand the value in thiscolumn is x

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example

Query 1:

Desc dual;

Query 2:select * from dual;

output: D

x

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Example

Select 4+4 from dual;

output: 4+4

8to view today's date

select Sysdate from dual;

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Select command with aggregate

functions

Aggregate functions are the Oracle functions

that takes collection of values as an input and

produce a single value as an output

1. Avg

2. Min

3. Max

4. Sum

5. Count

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Avg

It calculates the average value of specified

column

Select AVG(column-name)

from table-name;

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count

Counts the number ofrows in a table

1. count(*) , counts number ofrows in table

including duplicate and null values

2. Count(column-name) , counts the number

ofrows in a table that have a non null value

for specified column

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Select command with Group By clause

This clause creates a data set that contain severalsets ofrecord grouped together based on acondition

Syntax:select C1,C2,Cn

Aggregate-function(column-name)

From table-name

Where condition

Group By C1,C2,Cn;

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Example

If we want to see that how many students are

there in each branch

Select br

anch, count(r

ollno) no. of studentsFrom student

Group By branch;

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SELECT COMMAND WITHHAVING

CLAUSE

It is used to specify a condition on the Group byclause

Having clause is equivalent to where cluaseexcept that it acts on the record set but not onthe individual record

The main difference between where and havingclauses is that , the condition with where clauseis evaluated first and then it forms a group of

rows which satisfy the conditionwhereas,condition with having class is evaluatedafter the groups are formed by group by clause

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To show how many students are in CSE

branch

Select branch, count(rollno) No. of Students

From student

Group By b

ranch

Having branch = CSE;

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Nested queries

A query is a statement requesting the data

from database . A query written inside

another query is called sub-query.

Nested query can be formed using:

1. In connective

2. Non in connective

3. Exists

4. Non exists

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Data control language

It includes the commands that are related tothe security of database

Database administrator grants and revokes the

user privileges A user can be granted all the privileges or

some specific privilege

On an object user can perform only thoseoperations for which the privileges aregranted to him

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Various object privileges

ALTER:

DELETE

INSERT SELECT

UPDATE

INDEX With grant option

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DCL commands

syntax:Grant privileges

ON object-name

TO user-nameWITH GRANT OPTION;

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example

To provide insert and select privilege

SYNTAX: Grant insert, select

On Employee

To RAJ;

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To grant all the privileges

SYNTAX:

Grant All

On Employee

To SUNIL

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Revoke

SYNTAX:

Revoke privileges

On object-name From user-name;

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Join

When two tables get joined with the help of a

column that have same data type and size in

both the tables that relation is known as join

With the use of Join we can access the data

from multiple tables using single SQL

statement

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SYNTAX

select table1.column , table2.column

from table1 , table2

Wher

e table1.column = table2.column;The above statement selects the rows of two

tables , column for table1 and table2 must

have same data type as well as size

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Types of join

1. Cross join

2. Inner join or equi join

3. Outer

join Left outer join

Right outer join

4. Self join

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Cross join

It is also called as Cartesian product of two

tables

Cross join of two tables results in a new table

which contain each and every possible

combination ofrows of both the tables

The resultant table may contain duplicate

columns

Thus cross join is usually not preferred

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syntax

select table1.column , table2.column

from table1 , table2;

Cross join does not include the where clause in

its syntax

The above syntax is used when column name inboth the tables are same

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When the column name is different

SYNTAX:

select column1 , column2

fr

om table1, table2;

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Inner join

It is also called EQUI join

It is an improvement over cross join

It include wher

e clause in the select statement This is called equi join because condition

under where clause uses the equality operator

(=) to compare two values of table

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syntax

select table1.column, table2.column

from table1, table2

wher

e table1.column = table2.column;

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Cont..

Equi join first perform the cross join on two

tables and then shows only those rows which

satisfies the condition under where clause

If the where condition includes any operator

except = then it is called as non-equality join

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Outer join

The outer join is denoted by + operator

The + operator add the missing rows from first

table to the resultant table of inner join

For that row the values for corresponding

columns of second table may be null

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Types of outer join

1. Left outer join

Which includes all rows from first table

Example: X = Y (+)2. Right outer join

Which includes all the rows from second table

Example: X(+) = Y

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Self join

It is used to join the table itself

It performs the join operation on two copies

of same table

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VIEW

It is an oracle object that is used to implementthe security

A view is an imaginary table that is created

from some other base table Through view a user may be allow to access

specific column instead of accessing all thetables of database

Purpose of view is to provide security to thedata by restricting the access to the base table

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Cont..

Several views can be created from one base

table

A user working on a view is able to access only

those columns of base table that are included

in that view

View act like a window to the base table from

which it is created

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Types of views

1. Read only view

2. Updatable view

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Read only view

This view is used only to view the data

We are not allowed to do any changes in it

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Updatable view

In which we can perform insert , delete ,

update , and other operations

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Syntax for creating view

create view view-name

AS select column list

From table-name

Where condition;

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HOD

Dept_id HOD_Name

1 A

2 B

3 C

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Example of cross join

Select Name , HOD_name

From Department , HOD;

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output

Name HOD_Name

CSE A

IT A

ECE A

ME A

CSE B

IT B

ECE B

ME B

CSE C

IT C

ECE C

ME C

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EXAMPLE OF INNER JOIN

Show the name of departments and their

respective HODs

Select Name , HOD_Name

From department , HOD

Where department.dept_id = HOD.det_id;

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output

Name HOD_Name

CSE A

IT B

ECE C

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Example of self join

ID NAME HOD

1 W 2

2 X

3 Y 4

4 Z

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Show the names ofHODs with their teachers

Select a.name teacher , c.name HOD

From teacher a , teacher cWhere a.hod = c.id;

The above query creates two copies of tableteacher . The alias for first copy is a and alias forsecond copy is c

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output

teacher HOD

M N

O P

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PL/SQL

PL/SQL is a block structured query language

which combines the features of SQL with

procedural capabilities

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Disadvantages of SQL

1. SQL cannot be used for programming

because SQL does not provide the

programming techniques of condition

checking , looping and branching etc.

2. SQL statements are passed to oracle engine

one at a time which increases the traffic on

the network which results in decrease ofspeed of data processing

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Cont

3. On the occurrence of an error , the oracle

engine displays its own error message . SQL

does not allow the programmer to handle the

errors

To overcome above disadvantages of SQL ,

PL/SQL came into existance

/

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Advantages of PL/SQL

1. PL/SQL has SQL features as well as

procedural capabilities

2. PL/SQL sends entire block of sql statements

to oracle engine in one go ,thus reduces the

network traffic and results in icrease of

processing speed

3. It allows the programmer to display userfriendly error-message

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Cont

PL/SQL programs are portable i.e. , these can

run on any computer hardware and operating

system where oracle is installed

f / d

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Structure of PL/SQL Code BLOCK

A PL/SQL code block is divided into four

sections :

1. Declare section

2. Begin section

3. Exception section

4. End section

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structure

DECLARE

variable and constant declarations

BEGIN

SQL and PL statements

EXCEPTION

Err

or

handling statementsEND;

DECLARE i

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DECLARE section

Every code block starts with a declare section

It is used to declare and initialize variables

This section is optional

BEGIN

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BEGIN

It is an executable section which contain the

SQL and PL/SQL executable statements

It is compulsory section

This section includes all the data

manipulations, data retrieval , branching and

looping construct

E i

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Exception

It contains the user defined error handler

This section is executed only when an error

occures

E d ti

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End section

This section indicates the end of a code block

F d t l f PL/SQL

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Fundamentals of PL/SQL

Fundamentals of PL/SQL includes:

1. Character set

2. Operators

3. Literals4. Variables and consonants

5. Data types

6. Declarations

7. Assignment8. comments

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t

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operators

Operators can be classified into three groups

1. Arithmetic operators

2. Logical operators

3.C

omparison ope

rato

rs4. Literals:

numeric literals

character

stringboolean

V i bl d t t

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Variables and constants

Variable in PL/SQL is a named variable used to holdsome data values

Variable must start with a character and can befollowed by maximum of 29 other characters

Reserved words cannot be used as a variable name

Constant declaration is similar to variable declarationexcept that keyword constant is added to variablename and a value is assigned immediately

Ones a constant is de3clared no other assignment tothe constants is possible

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d l ti

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declarations

Before a variable can be used in the begin section, it must be declared in the DECLARE section

SYNTAX:

variable-name datatype(size);EXAMPLE:

Age Number(5);

A number(10,2);

Name Varchar2(20);

DOB Date;

Declaring constants

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Declaring constants

SYNTAX:

variable-name constant datatype(size) := value;

EXAMPLE:

Pi constant number(4,2) := 3.14;

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Example using assignment operator

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Example using assignment operator

A := 10;

B := c+d;

USING SELECT INTO CLAUSE

Select salary into sal from employee where

empid = 12;

comments

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comments

Single line: begins with double hyphen(--)

Multiline: begins with a (/*) and ends with

(*/)

How to read value during runtime

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How to read value during runtime

The symbol & is used to assign the value to

the variable during runtime

FOR EXAMPLE consider the num variable , to

read the value for this variable during runtimefollowing statement can be used:

Num := #

Cont

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Cont..

When the program will execute the system

will ask to enter the value and user can enter

any value

Enter the value of Num: 10

the value 10 is substituted at the place of

&Num

Num := 10;

Displaying user message on the screen

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Displaying user message on the screen

To display the message , the SERVEROUTPUT

should be set ON.

SYNTAX:

SQL> SET SERVEROUTPUT ON;

Now we can display any message using

DBMS_OUTPUT.PUT_LINE (hello);

Basic PL/SQL programs

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Basic PL/SQL programs

Write a PL/SQL code block to display the

message , hello.

Declare

Begin

dbms_output.put_line(hello);

END;

To add two numbers

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To add two numbers

Declarea number(2);

b number(2);

c number(2);

Begin

a:=5;

b:= 4;

C:= a+b;

Dbms_output.put_line(sum=||c);

END;

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Conditional control

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Conditional control

IF-THEN

IF-THEN-ELSE

IF-THEN-ELSEIF

IF THEN

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IF THEN

IF condition then

sequence of statement;

END IF;

IF THEN ELSE

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IF THEN ELSE

If condition then

statements1;

ELSE

statements2;

END IF;

If-then-elseif

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If-then-elseif

IF condition1 THEN

statements1;

ELSIF condition2 THEN

statement2;

ELSE

Statement3;

END IF;

Iterative control

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Iterative control

LOOP

WHILE-LOOP

FOR-LOOP

loop

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loop

The keyword LOOP is placed before the first

statement in the sequence and the keyword

END LOOP after the last statement in the

sequence To exit from the loop EXIT-WHEN statement

can be used

syntax

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syntax

LOOP

sequence of statements;

EXIT WHEN condition;

END LOOP;

The loop will complete when the condition under

EXIT-WHEN clause is true

If the condition is omitted from the above syntax,then the loop will terminate unconditionally

EXAMPLE

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EXAMPLE

Write a program to display number from 1to 10Declare

i number (2);

Begin

i:= 1;LOOP

dbms_output.put_line(i);

i:=i+1;

EXIT WHEN i>=10;

END LOOP;

END;

While loop

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While loop

Syntax:

WHILE condition LOOP

sequence-of-statements;

END LOOP;

Cont

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Cont

Before executing the sequence of statements ,the condition is evaluated.

If it results in TRUE , then the body of loop isexecuted and the control goes to the top of theloop.

Thus the body of loop is executed each time thecondition is TRUE.

When the condition becomes FALSE, the bodywill no get executed and the control goes to thestatement immediate below the loop.

example

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example

Write a program to print square of numbers from 1 to 10.Declare

a number(2);

Begin

a:=1;WHILE a

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For loop

The FOR-LOOP statement is used to specify a

range of integers and then executes a

sequence of statements, once for each integer

in the range Unlike WHILE-LOOP, the number of iterations

through a FOR loop is known before the loop

is entered

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Cont..

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Cont..

The lower and upper bounds are the integervalues separated by double dot(..) and specifya range.

As long as the value of variable counterliesbetween the specified ranges, the sequence ofstatements keep on executing.

The FOR loop initialize and increment the

counter automatically Keyword REVERSE is optional

Cont..

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Cont..

If the reverse option is not used then, thevariable counter is assigned values ranging fromlower bound to upper bound

EXAMPLE:

FOR counter IN 1..5

LOOP

sequence- of-statements;

END LOOP;

Here, counter is assigned values 1,2,3,4,5.

Cont..

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Cont..

If REVERSE option is used then, counter isassigned values ranging from upper bound tolower bound

EXAMPLE:

FOR counter IN REVERSE 1..5

LOOP

sequence of statements;

END LOOP;

Here counter is assigned values 5,4,3,2,1.

EXAMPLE

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EXAMPLE

Write a PL/SQL block to display the table of 2DECLARE

Total number(4);

i number(2);

BEGINFOR i IN 1..10

LOOP

total:=2*I;

dbms_output.put_line(2*||i||=||tatal);

END LOOP;

END;

Sequence control

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Sequence control

GOTO statement transfer the flow of control

to a specified label unconditionally.

The label is marked using tags .

Labelname is a user defiened name and it can

appear either above or below the GOTO

statement.

SYNTAX

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GOTO label-name;

Example

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p

Write a program to find the larger of two numbers using GOTO statement.DECLARE

num1 number(2);

num2 number(2);

BEGIN

num1:=&num1;

num2:=&num2;

IF num1>num2 THEN

GOTO O1;

ELSE

GOTO O2;

END IF;

dbms_output.put_line(g reater is num1 = ||num1);

GOTO O3;

dbms_output.put_line(g reater is num2 = ||num2);

dbms_output.put_line(SU CCESSFULLY);

END;

DATABASE TRIGGERS

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It is the stored procedure that is automatically

executed in response to certain events on a

particular table or view in a database.

An event on a table can be INSERT, DELETE, orUPDATE statement on the table

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Triggering event or statement

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gg g

It is an SQL statement that makes a trigger to fire

There are typically three triggering events thatcauses trigger to fire:

1. INSERT event(when a new record is beinginserted into table).

2. UPDATE event(when a record is being changedin a table).

3. DELETE event(when a record is being deletedfrom a table) .

Triggerrestriction

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gg

It is a Boolean expression that must be truefor a trigger to fire

When an event occurs and Triggerrestriction

is evaluated to true then, only the t

rigge

rwillfire

But if Triggerrestriction evaluated to be false,the Trigger will not fire

A Triggerrestriction is specified using WHENclause

TRIGGER ACTION

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It is a PL/SQL code which is executed when an

event occurs and triggerrestriction is

evaluated to TRUE

Types of triggers

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yp gg

1. ROW triggers:

A ROW trigger is fired for each row affected by a

triggering statement

Statement trigger

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gg

Statement trigger is fired once for a triggering

statement, regardless of the no. ofrows

affected by triggering statement

Classification on the basis of execution

time

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time

BEFORE trigger

AFTER trigger

BEFORE trigger

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It executes its trigger action before the

triggering statement

It can be used when the trigger action must be

executed before the triggering statementcompletes

AFTER triggers

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Executes the trigger action after triggering

statement is executed

It can be used when the triggering statement

must be executed before executing the triggeraction

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EXAMPLE

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Write a prog to create a trigger which will tell

about the operation performed on the

student table

program

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Create or Replace Trigger OprBefore INSERT or UPDATE or DELETE

ON STUDENT

BEGIN

IF INSERTING THEN

dbms_output.put_line(Operation performed is INSERT);

ELSE UPDATING THENdbms_output.put_line(Operation performed is update);

ELSE

dbms_output.put_line(Operation performed is DELETE);

END IF;

END;

Enabling or Disabling Triggers

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For disabling the trigger:

SQL> ALTER TRIGGER TRIGGERNAME Disable;

Example:

SQL> Alter Trigger check Disable;

Cont..

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For enabling trigger

Syntax:

SQL> Alter Trigger TriggerName Enable;

Disabling all the triggers of table at once:

Syntax:

SQL> ALTER Table TableName Disable All

Triggers;

Dropping a trigger

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Drop Trigger TriggerName;

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Steps needs to work with cursor

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Declare a cursor

Open a cursor

Fetch orread from cursor

Close a cursor

Types of cursor

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Implicit cursor

Explicit cursor

Implicit cursor

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It is a work area that is declared, opened and

closed internally by the oracle engine

The user is not involved in managing the

cursor

PL/SQL declares a cursor implicitly for all SQL

data manipulation statements

Explicit cursor

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It is a work area that is declared, opened and

closed externally by the user

It is also called USER-DEFINED cursor

It is declared in the DECLARE part of PL/SQLblock

Attributes of cursor

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To keep track of current status of cursor,

PL/SQL uses some attributes which are

common to both implicit and explicit cursor

ATTRIBUTES

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Attribute Meaning

%ISOPEN Returns TRUE if cursor is open,

FALSE otherwise.

%FOUND Returns TRUE ifrecord was

fetched successfully, FALSE

otherwise.

%NOTFOUND Returns TRUE ifrecord was not

fetched successfully, FALSE

otherwise

%ROWCOUNT Returns number ofrecords

processed from cursor

Implicit cursor

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Implicit cursor attributes are used to access

the information about the status of last

INSERT, UPDATE, and DELETE or single row

select statement Implicit cursor uses same set of general

attributes but proceeded with cursor name

i.e., SQL.

Implicit cursor attributes

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SQL%ISOPEN

This is always return FALSE because the oracle

engine closes the implicit cursor automatically

after executing SQL statement.

EXAMPLE

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Write a PL/SQL block to display a message that whether arecord is updated or not using SQL%FOUND andSQL%NOTFOUND.

BEGIN

Update student set city = pune where rollno=&rollno;

IF SQL%FOUND THENdbms_output.put_line(record updated);

END IF;

IF SQL%NOTFOUND THEN

dbms_output.put_line(record not updated);END IF;

END

To count number ofrows affected by

update statement

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update statement

DECALREnum number(2);

BEGIN

Update student set grade = b wheregrade=c;

num := SQL%ROWCOUNT;

dbms_output.put_line(Row affected = num);END;

Explicit cursor

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When a query returns multiple rows, user canexplicitly declare a cursor to process the rows

It is declared in the DECLARE section of

PL/SQL block All the general attributes of a cursor are

applicable to this cursor

Steps in handling explicit cursor

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Explicit cursor handling needs following steps tobe followed:

1. Declare the cursor in DECLARE part of PL/SQLblock

2. Open the cursor3. Using a loop, fetch data from cursor one row at

a time into memory variables and process thedata stored in the memory variable as required

4. EXIT f rom loop when processing is complete5. CLOSE the cursor

Declaring a cursor

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A cursor must be declared before referencingin other statement

When cursor is declared , it is given a name

and is associated with a specific query

syntax

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CursorCursorName IS SELECT statement;

EXAMPLE:

CursorC IS SELECT rollno from student

where id = 102;

Opening a cursor

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Opening a cursor executes the query andidentifies the result set, which consist of all

the rows that meet the query search criteria

SYNTAX:Open CursorName;

Fetching record from cursor

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After opening a cursor, FETCH statement isused to load the rows from the result set into

the memory variable but, one row at a time

SYNTAX:FETCHCursorName INTO variables;

EXAMPLE:

FETCHC INTO rollno, name;

Closing a cursor

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It disable the cursor and the result setbecomes undefined

Once a cursor is closed it can be reopen again

SYNTAX:

CLOSE CursorName;

Write a prog to display the name of

the student belonging to CSE branch

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g g

DECLARECURSOR C IS select name from student where branch = cse;

BEGIN

Open C;

LOOPFetch C into name;

EXIT When C%NOTFOUND;

dbms_output.put_line(name);

END LOOP;

Close C;END;

subprograms

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The named PL/SQL code blocks that can accept

parameters and can be invoked are called

SUBPROGRASMS

types

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Procedures

functions

procedure

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A procedure or a function is a group of SQLand PL/SQL statements that is used to performa specific task.

Basically procedure is used to perform anaction where as function is used to compute avalue.

Another difference is that procedure may

return no value but function must return avalue

Stored procedure

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It is a procedure that has been compiled andstored in any of the oracle engines system

table

The basic purpose of subprograms is toachieve:

1. Modularity

2. reusability

modularity

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It allow the programmer to divide a programinto more than one well defined unit calledMODULES

Modularity results in:

1. Extensibility, which enables us to create newmodules without affecting the existingmodules

2. Maintainability, which makes the modules tobe managed easily.

Reusability

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It enables a subprogram to be used in anynumber of applications

Creating procedures

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DECLAREglobal variable declaration;

procedure procedureName

(argument IN/OUT datatype,)

IS/AS

variable and const declaration;

BEGIN PL/SQL statements;

EXCEPTION

exception handling statements;

END ProcedureName;

BEGIN

executable statements;

procedure calling;

EXCEPTION

END

To multiply two numbers using

procedure

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DECLARENum1 Number(2);

Num2 Number(2);

Mul Number(4);

Procedure multiplication(Num1 IN Number, Num2 IN Number, Mul OUTNumber) IS

BEGIN

Mul:=Num1*Num2;

End Multiplication;

Begin

Num1:=&Num1

Num2:=&Num2

Multiplication(Num1,Num2,Mul);..procedure calling

dbms_output.put_line(Mul);

END

Creating a stored procedure

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Create Or Replace Procedure ProcedureName(Argument IN/OUT/IN OUT Datatype,..)

IS/AS

Variable and constant declaration;

Begin

PL/SQL statements;

Exception

exception handling statement;End;

Stored procedure to add two numbers

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Create Or Replace Procedure Addition(Num1IN Number, Num2 IN Number, Sum OUT

Number)IS

BeginSum:=Num1+Num2;

End;

Display sum of two numbers by calling

the addition stored procedure

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DeclareNum1 Number(2);

Num2 Number(2);

Sum Number(2);

Begin

Num1:=&Num1;

Num2:=&Num2;

Addition(Num1,Num2,Sum);

dbms_output.put_line(Addition is||Sum);

End;

Creating a function

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DeclareGlobal Variable Declaration;

Function FunctionName

(Argument IN Datatype,..)

Return DataType

IS/AS

var

and const declar

ation;Begin

PL/SQL Statements;

Exception

End FunctionName;

Begin

executable statements;

Function calling;

End;

Deleting stored procedure

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Drop Procedure ProcedureName;

packages

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A package is an oracle object which is used tobundle various objects like variables,

constants, cursor and subprograms

A package has two parts:

1. Package specification

2. Package body

Cont..

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Specification declares the variables, constants,cursors and subprograms

Body defines cursor and subprograms and

thus implement the specification

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Creating a package

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Package Specification

Create Or Replace Package PackageName AS

Function FunctionName(Arg List)Return

Datatype;

Procedure ProcedureName(Arg list);

End PackageName;

Package body

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Create O

rReplace Package Body PackageName ASFunction FunctionName(Arg list)Retrn Datatype

IS/AS

var and const declaration;

Begin

pl/sql statements;

Exception

Exception handling statements;

End FunctionName;

Procedure ProcedureName(arg list)IS/AS

variable and const declaration;

Begin

pl/sql statements;

Exception

End ProcedureName;

End PackageName;

Calling objects of package

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To call either a function or a procedurecontained in a package , dot(.) notation is used

as follows:

Syntax:PackageName.FunctionName(actual arg);

PackageName.ProcedureName(actual arg);

Deleting a package

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Drop Package PackageName;

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