DELIMITER ||
CREATE TRIGGER tri_video_class AFTER UPDATE ON 数据库名.表名称 FOR EACH ROW begin
IF((old.status != new.status) or (old.status IS NULL && new.status IS NOT NULL))
THEN
UPDATE 数据库名称.数据表名称
SET lession_status = new.status
WHERE teacherId = old.teacherId AND s_time = old.s_time;
END IF;
END||
DELIMITER ;