ALTER PROCEDURE proc_name [characteristic ...]

characteristic:
    COMMENT 'string'
  | { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
  | SQL SECURITY { DEFINER | INVOKER }

This statement can be used to change the characteristics of a stored procedure. More than one change may be specified in an ALTER PROCEDURE statement. However, you cannot change the parameters or body of a stored procedure using this statement; to make such changes, you must drop and re-create the procedure using DROP PROCEDURE and CREATE PROCEDURE.

As of MySQL 5.0.3, you must have the ALTER ROUTINE privilege for the procedure. By default, that privilege is granted automatically to the procedure creator. This behavior can be changed by disabling the automatic_sp_privileges system variable. See Section 17.2.2, “Stored Routines and MySQL Privileges”.