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Oracle Functions
Oracle function is a subprogram that calculates a value.
CREATE FUNCTION
As with other programming languages, you can create your own functions in Oracle.
Syntax
CREATE [OR REPLACE] FUNCTION_function name_id
[ (parameter_id [, parameter_id, ...]) ]
RETURN IS_data type_id | AS
[local ads_id]
BEGIN
executable offers_id
[EXCEPTION
exception handler_ids]
END [function_name_id];
When creating a procedure or function, you can define three types of parameters that can be declared:
- IN – A parameter can refer to a procedure or function. The value of the parameter cannot be changed by the procedure or function.
- OUT – The parameter cannot refer to a procedure or function, but the parameter value can be changed by the procedure or function.
- IN OUT – The parameter can reference the procedure or function and the parameter values can be changed by the procedure or function.
Let’s consider an example of how to create a function in Oracle
CREATE OR REPLACE Function FindCourse
( name_in_id IN varchar2_id )
RETURN number
IS
cnumber number_id;
cursor c1 is
SELECT course_number_id
FROM courses_tbl_id
WHERE course_name_id = name_in_id;
BEGIN
open c1;
fetch c1 into cnumber_id;
if c1%notfound then
cnumber_id := 9999;
end if;
close c1;
RETURN cnumber_id;
EXCEPTION
WHEN OTHERS THEN
raise_application_error(-20001,'An error was encountered - '||SQLCODE|' -ERROR- '||SQLERRM);
END;
This function is called the FindCourse. It has one parameter name_in and returns a number. The function returns course_number if it finds a match based on course_name. Otherwise, it returns 99999.
You can refer to your new function in an SQL query as follows:
SELECT course_name_id, FindCourse(course_name_id) AS course_id
FROM courses_id
WHERE subject = 'Mathematics';
DROP FUNCTION
Once you have created a feature in Oracle, you may need to remove it from the database.
The syntax for deletion is a function in Oracle
DROP FUNCTION_function name_id;
- function_name_id The name of the function you want to delete.
Let us consider an example of how to remove a function in Oracle.
DROP FUNCTION FindCourse_id;
In this example, we remove a function called FindCourse.
Oracle Functions – Overview and Core Concepts
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