————————————前面已建触发器——————————————mysql> create trigger upd_check before update on tb    -> for each row    -> begin    -> if new.a < 0 then    -> set new.a =0;    -> elseif new.a > 100 then    -> set new.a = 100;    -> end if ;    -> end ; //1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '-> for each row    -> begin    -> if new.a < 0 then    -> set new.a =0; ' at line 2