MySQL in a Nutshell, 2nd Edition

Name

ALTER FUNCTION

Synopsis

ALTER FUNCTION stored_procedure
  [{CONTAINS SQL|NO SQL|READS SQL DATA|MODIFIES SQL DATA} |
    SQL SECURITY {DEFINER|INVOKER} |
    COMMENT 'string']

This statement changes the characteristics of an existing user-defined function. You cannot change the function itself with it. To do that, you need to delete the function with DROP FUNCTION and create a new procedure with CREATE FUNCTION. See the description of CREATE FUNCTION later in this chapter for an explanation of each characteristic.

There are three types of characteristics you can set or change with this statement: the types of interaction with the server, the user recognized for SQL security, and a comment. Each type may be given in a space-separated list, in any order. See CREATE FUNCTION later in this chapter for a discussion of the characteristics. The COMMENT clause replaces any existing comment. To clear a comment without inserting another, give two quotes with nothing between them.

This statement requires the CREATE ROUTINE privilege. The ALTER ROUTINE and EXECUTE privileges are granted to the user and host account that creates or alters a function, by default.

Here is an example using this statement, in which a function shown in the example for the CREATE FUNCTION statement is altered:

ALTER FUNCTION date_reformatted
SQL SECURITY INVOKER
COMMENT "Converts a string date like 'Dec. 7, 2007' to standard format.";