MySQL_Trigger

    1. Create

    i. Trigger with single action

create trigger tri after insert on t_book2 for each row update t_bookType set bookNumber=bookNumber+1 where new.bookTypeId=t_bookType.id;
insert into t_book2 values (null, 'java好', 110, '张神',1);

    ii. Trigger with multi action

delimiter ||
create trigger tri2 after delete on t_book2 for each row
begin
update t_bookType set bookNumber=bookNumber-1 where old.bookTypeId=t_bookType.id;
insert into log values(null, now(), '在t_book2里删除了一条数据');
delete from t_test where old.bookTypeId=t_test.id;
end ||
delimiter;

    before:

    After:

delete from t_book2 where id=6;

    2. Show trigger

show triggers;

    3. Drop trigger

drop trigger tri2;

转载于:https://my.oschina.net/u/2363350/blog/671884