mysql包括历史记录到timee1的触发器，那里不对了，为什么保存不了

CREATE TRIGGER trigger_timee1 BEFORE UPDATE ON timee
FOR EACH ROW begin
insert into timee1 values
(:old.timeid,:old.chexing);
end;

delimiter //
drop trigger stu_info_update_trigger//
create trigger stu_info_update_trigger before update
on stu_info FOR EACH ROW

begin

insert into stu_info_bak values(old.id,old.age,old.skill);
end;//