Author Topic: Creating Procedures  (Read 2731 times)

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Creating Procedures
« on: June 06, 2009, 10:36:19 AM »
In Oracle, you can create your own procedures.

The syntax for a procedure is:

Code: [Select]
CREATE [OR REPLACE] PROCEDURE procedure_name
    [ (parameter [,parameter]) ]
IS
    [declaration_section]
BEGIN
    executable_section
[EXCEPTION
    exception_section]
END [procedure_name];


When you create a procedure or function, you may define parameters. There are three types of parameters that can be declared:

1.IN - The parameter can be referenced by the procedure or function. The value of the parameter can not be overwritten by the procedure or function.
2.OUT - The parameter can not be referenced by the procedure or function, but the value of the parameter can be overwritten by the procedure or function.
3.IN OUT - The parameter can be referenced by the procedure or function and the value of the parameter can be overwritten by the procedure or function.


The following is a simple example of a procedure:

Code: [Select]
CREATE OR REPLACE Procedure UpdateCourse
   ( name_in IN varchar2 )
IS
    cnumber number;

    cursor c1 is
    select course_number
      from courses_tbl
      where course_name = name_in;

BEGIN

open c1;
fetch c1 into cnumber;

if c1%notfound then
     cnumber := 9999;
end if;

insert into student_courses
( course_name,
  course_number)
values ( name_in,
                cnumber );

commit;

close c1;

EXCEPTION
WHEN OTHERS THEN
      raise_application_error(-20001,'An error was encountered - '||SQLCODE||' -ERROR- '||SQLERRM);
END;

This procedure is called UpdateCourse. It has one parameter called name_in. The procedure will lookup the course_number based on course name. If it does not find a match, it defaults the course number to 99999. It then inserts a new record into the student_courses table.