Syntax
------

DROP FUNCTION [IF EXISTS] f_name

Description
-----------

The DROP FUNCTION statement is used to drop a stored function or a
user-defined function (UDF). That is, the specified routine is removed from
the server, along with all privileges specific to the function. You must have
the ALTER ROUTINE privilege for the routine in order to drop it. If the
automatic_sp_privileges server system variable is set, both the ALTER ROUTINE
and EXECUTE privileges are granted automatically to the routine creator - see
Stored Routine Privileges.

IF EXISTS
---------

The IF EXISTS clause is a MySQL/MariaDB extension. It prevents an error from
occurring if the function does not exist. A NOTE is produced that can be
viewed with SHOW WARNINGS.

For dropping a user-defined functions (UDF), see DROP FUNCTION UDF.

Examples
--------

DROP FUNCTION hello;
Query OK, 0 rows affected (0.042 sec)

DROP FUNCTION hello;
ERROR 1305 (42000): FUNCTION test.hello does not exist

DROP FUNCTION IF EXISTS hello;
Query OK, 0 rows affected, 1 warning (0.000 sec)

SHOW WARNINGS;
+-------+------+------------------------------------+
| Level | Code | Message                            |
+-------+------+------------------------------------+
| Note  | 1305 | FUNCTION test.hello does not exist |
+-------+------+------------------------------------+

URL: https://mariadb.com/kb/en/drop-function/