xxxxxxxxxx
DELIMITER $$
CREATE TRIGGER product_name_validator
BEFORE UPDATE
ON products FOR EACH ROW
IF NEW.product_name<>OLD.product_name
THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Product name is read-only and it can not be changed.';
END IF $$
DELIMITER ;
xxxxxxxxxx
DELIMITER $$
CREATE TRIGGER trigger_name
BEFORE UPDATE
ON table_name FOR EACH ROW
BEGIN
-- statements
END$$
DELIMITER ;
Code language: SQL (Structured Query Language) (sql)