Mysql created_at updated_at triggers

ALTER TABLE xxxxxx
ADD created_at TIMESTAMP DEFAULT '0000-00-00 00:00:00',
ADD updated_at TIMESTAMP DEFAULT '0000-00-00 00:00:00';
CREATE TRIGGER xxxxxx_create BEFORE INSERT ON `xxxxxx`
FOR EACH ROW SET NEW.created_at = NOW(), NEW.updated_at = NOW();
CREATE TRIGGER xxxxxx_update BEFORE UPDATE ON `xxxxxx`
FOR EACH ROW SET NEW.updated_at = NOW(), NEW.created_at = OLD.created_at;

thanks bro.