MySQL - Function

mysql> CREATE FUNCTION f()

       RETURNS int DETERMINISTIC

       RETURN 2;

mysql> SELECT f();

mysql> CREATE FUNCTION addTwo(x INT)

       RETURNS int DETERMINISTIC

       RETURN x + 2;

mysql> SELECT addTwo(3);

mysql> CREATE FUNCTION maxId()

       RETURNS int DETERMINISTIC

       RETURN (SELECT MAX(id) FROM data);

mysql> SELECT maxId();

MySQL - Function