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Packages:

It is a schema object.

It is a group of logically related procedures or functions or variable, cursor and types into a

single unit.

If STUDENT is a table:

studentinsert is a procedurestudentupdate is a procedure

studentdelete is a procedure

studentcount is a procedurestudentsearch is a procedure

Instead of creating several individual procedures, we create a package.

When compared to procedures packages have some additional advantages:

Information hidingPerformance Improvement

pkgstudent

Client is calling student insert procedure

1. First it loads procedure from database into oracle SGA-- running copy -- reading from file to

SGA -- I/O2. Then it executes called procedure.

What can we define inside a package?

1. Procedures

2. Functions

3. Variables4. Cursors & ref cursor

5. Types

6. Exceptions

Parts of a Package:

1. Package Specification-- Declaration of package members (procedures, function, variables...)

-- That means individual syntax of procedures, functions....

2. Package body -- Optional-- Contains code of package members.

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-- Package body is not required, when package specification does not contain any procedures or

functions.

All members of package divided into two types:

1. Public-- All members declared in specification are called public.

-- All public members can be called from outside of package.

2. Private-- All members declared in package body and not in specification are called private.

-- Private members cannot be called from outside of package; it should be called from within

package body.

How can we call package members?

using "." nototion.

.;

First we have to declare package specification

Then create package body.

Syntax:

create or replace package

ISvariablename datatype; -- normal variable declare syntax

procedure (withparameters);

function (withparameters) return ;

........................................................................end;

Creating Package body:

create or replace package body

is-- Code for all procedures and functions is written here.

-- Specified in pakage specification.

procedure (withparameters)

isbegin

exception

end;

fucntion(withparameters) return

is

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begin

end;

..............................................

end;

Package for implementing airthmetic operations:

add2valuessub2values

mul2values

div2values

create or replace package mathoperations

is

function add2values(a number, b number) return number;

function sub2values(a number, b number) return number;function mul2vaues(a number, b number) return number;

function div2values(a number, b number) return number;msg varchar2(100):='welcome';

end;

create or replace package body mathoperations

is

function add2values(a number, b number)

return numberis

res number(4);

begin

res:= a + b;return res;

end;

end;

To find the errors:

select * from all_errors where name='MATHOPERATORS'

set serveroutput on

declarec number(4);

begin

dbms_output.put_line(mathoperations.msg); -- acessing packge varibale1begin

dbms_output.put_line(mathoperation.msg);

c:=mathoperation.add2values (3,4);

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dbms_output.put_line('sum is' || c);

end;

We can have two variables with same name in packages. Oracle recogizes depending on

datatypes. The datatypes should not be the same.

Dropping a package:

drop package body; -- drops only bodydrop pakcage -- this drops entire package.

HW ASSIGN:

create a table called student

id, firstname, lastname, age, gender

Create a package called stgpackage with following members

1. stdinsert -- for inserting a record into student table...Note: id should be generated automatically... No need to pass as parameters.

2. stdupdate -- for updating a record. -- It should return status-- All parameters should be passed... Update is based on id

3. Create a procedure for delete std based on id and based on name -- status should be returned.

4. Display student... Either based on id or name.

5. getstudentcount -- Funtion for getting std count...

-- calling programs for testing each package members.