trigger Throw error message

[natukunda liz]

i need a trigger to give an error message if invalid data is inserted.here is my trial and its not working. please help on error handling in mysql. thank you.

mysql> DELIMITER //
mysql> CREATE TRIGGER TR_CHECKCONSTRAINT
-> BEFORE INSERT ON TEST_CHECKCO
-> FOR EACH ROW
-> BEGIN
-> DECLARE msg varchar(255);
-> IF NOT new.AGE = 50 THEN
-> SET msg = 'INVALID DATA'
-> SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
-> END IF;
-> END
-> //