1. SQL Stored Procedures and Functions Presented by: Dr. Samir Tartir
Session - 6 Sequence – 8
SQL
Stored Procedures and Functions
Presented by: Dr. Samir Tartir

2. Outline PL/SQL Stored Procedures Stored Functions
Running Procedures and Functions

3. Stored Procedures Defined set of actions written using PL/SQL
Two parts
Procedure specification
Procedure body
Procedure parameters can be used to pass values from the caller to the procedure or the other way around.
Must specify data type.

4. Parameters
Create or replace procedure Increase_salary_find_tax
(increase_percent IN NUMBER:=7,
sal IN OUT NUMBER,
tax OUT NUMBER) AS
IN means the procedure can read an incoming value from that parameter when the procedure is called
OUT means the procedure can use that parameter to send a value back to what called it
increase_percent has a default value of 7

5. Example - 1
CREATE OR REPLACE PROCEDURE hello AS Greetings VARCHAR(20); BEGIN Greetings:= 'Hello World'; DBMS_OUTPUT.PUT_LINE(Greetings); END hello; /

6. Example - 2
CREATE OR REPLACE PROCEDURE increase ( oldprice NUMBER, percent NUMBER := 5, newprice OUT NUMBER) AS BEGIN newprice:=oldprice+oldprice*percent/100; END increase; /

7. Example - 3
CREATE OR REPLACE PROCEDURE NewSal( ESSN NUMBER, Percent NUMBER, NEWSAL OUT NUMBER) AS SAL NUMBER; BEGIN SELECT SALARY+SALARY*Percent/100 INTO NEWSAL FROM EMPLOYEE WHERE SSN = ESSN; END NewSal; /

8. Stored Functions
CREATE OR REPLACE FUNCTION discount ( amount NUMBER, percent NUMBER := 5) RETURN NUMBER AS BEGIN IF (amount>=0) THEN return (amount*percent/100); ELSE return(0); END IF; END discount; /

9. Compilation Errors
When creating the procedure, if there are errors in its definition, they will not be shown
To see the errors of a procedure called myProcedure, type
SHOW ERRORS PROCEDURE myProcedure
For functions, type
SHOW ERRORS FUNCTION myFunction
The following statements shows errors of the last compiled code
SHOW ERROR (or SHO ERR for short)

10. Running a Procedure or Function
set serveroutput on
EXEC hello;
declare
out number;
begin
increase(10,5,out);
DBMS_OUTPUT.PUT_LINE(out);
end; /
declare
out number;
begin
NewSal( ,10,out);
DBMS_OUTPUT.PUT_LINE(out);
end; /
out := discount(100,5);

11. SUMMARY
Oracle uses PL/SQL to include business logic right in the database directly.
DBMS’s use stored procedures and stored functions to call server-side from middle-tear programs

12. Resources & References
Dr. Samir Tartir
Website:
Fundamentals of Database Systems by El Masri & Navathe. Publisher : Addison-Wesley, 5th edition, 2006.