MySQL_Trigger

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);

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;

delete from t_book2 where id=6;

show triggers;

drop trigger tri2;