tigger 触发器

用update前的列就用old，要引用update后的列就用new

old为正在删除信息   new 正在插入的信息

//删除tab1表记录后自动将tab2表中对应的记录删去

DROP  TRIGGER    IF EXISTS   t_afterdelete_on_tab1;

CREATE  TRIGGER    t_afterdelete_on_tab1

AFTER  DELETE  ON   tab1

FOREACH ROW

BEGIN

delete  from   tab2  where   tab2_id=old.tab1_id;

END;

DELETEF ROM tab1  WHERE    tab1_id='0001';

---

delimiter $

create  trigger t_good

after INSERT

on good_order

for each row

BEGIN

UPDATE good_store set gnum=gnum-new.onum  where id = new.oid;

end;

$$

delimiter;

insert into good_order values(null,1,10);

---

use hh;

DROP TRIGGER if EXISTS t_del;

delimiter $$

create trigger t_del

BEFORE DELETE

on student

for each row

BEGIN

DELETE from  sc where scsno = old.sno;

END;

$$

delimiter;

DELETE from student where sno ='200215122';