MYSQL触发器更新本表数据异常

ERROR 1442 (HY000): Can't update table '120_xx_220416' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
如果出现这个问题，则是循环的调用造成的

触发器里面，不要出现insert/update

解决办法如下：
drop TRIGGER if EXISTS 120_xx;
delimiter //
CREATE TRIGGER 120_xx
    before INSERT
    ON 120_xx_220416
    FOR EACH ROW
    BEGIN
    set NEW.ask_md5 = md5(CONCAT(NEW.title,NEW.answer));
    END;
//

delimiter //
CREATE TRIGGER 120_xx_update
    before update
    ON 120_xx_220416
    FOR EACH ROW
    BEGIN
    set NEW.ask_md5 = md5(CONCAT(NEW.title,NEW.answer));
    END;
//