Creating Procedures

In Oracle, you can create your own procedures.

The syntax for a procedure is:

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:

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.

Download CREATINGPROCEDURES.pdf.html