stored procedures and functions

1. Stored Procedure and Functions

2. What are Strored Procedures?
• Stored Procedure are named PL/SQL blocks.
• Stored Procedure is a logical group of SQL and
PL/SQL statements that perform some specific
action
• Stored in database as database objects.
• Are compiled ONLY at the time of their creation
or modification

3. Advantages of Stored Procedures
• Improve database performance
– Reducing information sent over network
• Memory Allocation
– Only single copy of stored procedure is loaded
into memory for execution by multiple users.
• Productivity
– Redundant code can be avoided

4. Advantages of Stored Procedures
• Integrity
– Common set of procedures reduces committing
coding errors
• Memory Allocation
– Only single copy of stored procedure is loaded into
memory for execution by multiple users.
• Productivity
– Redundant code can be avoided

5. Anonymous Pl/SQL vs Stored
Procedures
• Anonymous PL/SQL is unnamed PL/SQL block
whereas Stored Procedure is named block.
• Anonymous PL/SQL subsequent reuse is not
possible.
• Anonymous PL/SQL compiled each time
submitted to Oracle whereas Stored
procedure is stored as database object.s

6. How to create Stored Procedures
CREATE [OR REPLACE] PROCEDURE procname
(parameter1 MODE datatype [,parameter2 MODE datatype...])
AS
[declare]
....
BEGIN
statement(s);
END [procname];

7. MODES of Parameters
• IN Mode
– Default
– Pass values to the procedure being called
– IN parameters acts like constant and cannot
assigned value.

8. MODES of Parameters
• OUT Mode
– Returns values to caller
– OUT parameters is uninitialized and cannot be
assigned to another variable.
• IN OUT Mode
– Pass initial value to procedure and return updated
values
– Can be initialised or assigned to other

9. STORED FUNCTIONS

10. What are Stored Functions
• Store Function is same as Stored Procedure except that
– FUNCTION return value Procedure not
CREATE OR REPLACE FUNCTION functionname
(parameter MODE datatype....)
RETURN returntype
AS
declare
BEGIN
statements;
END functionname;

11. Obtaining Procedure Created by You
• To see names of procedure
SELECT * FROM user_objects
WHERE object_type=‘PROCEDURE’
• To view source code of procedure
SELECT Text FROM user_source
WHERE name=‘procedurename’;

12. DROPPING
DROP PROCEDURE procedurename;
DROP FUNCTION functionname;

13. PACKAGES

14. What are Packages
• Packages are the schema objects that groups logically
related PL/SQL objects.
• Compiled and stored in database.
• What goes in PL/SQL?
– Types
– Variables and Constants
– Cursors
– Procedure and Function
– Exception declaration

15. Advantages of Packages
• Modularity
– Encapsulate logically related types
• Information Hiding by declaring it as public or
private

16. Parts of Package
• Specification
– Declare types, constants, cursors, exception etc.
– List package resources available to resources
– Its a public declaration visible to apps
– Compulsory
• Body
– Implements or define cursors or subprograms
– Private declaration hidden from apps
– Optional

17. CREATE OR REPLACE PACKAGE pkgname
IS
-- all declaration statement
END pkgnmae
CREATE OR REPLACE PACKAGE BODY pkgname
IS
-- all definition