how to use a trigger to validate input data

-- validate email
CREATE TRIGGER `person_validate_insert`
	BEFORE INSERT
	ON `person`
	FOR EACH ROW
BEGIN
	IF NEW.`email` NOT LIKE '%_@%_.__%' THEN
		SIGNAL SQLSTATE VALUE '45000'
			SET MESSAGE_TEXT = '[table:person] - `email` column is not valid';
	END IF;
END;