触发器的示例

create table cat_tb
(
  cat_id int primary key,
  cat_name varchar(20)
)
go
insert into cat_tb values(100,'数码电子')
insert into cat_tb values(200,'化妆品')
insert into cat_tb values(300,'家具')
go

create table sub_tb
(
 sub_id int primary key,
 sub_name varchar(20),
 cat_id int foreign key(cat_id) references cat_tb
)

go 
insert into sub_tb values(1000,'电脑',100)
insert into sub_tb values(2000,'鼠标',100)
insert into sub_tb values(3000,'美容品',200)
insert into sub_tb values(4000,'桌子',300)
insert into sub_tb values(5000,'凳子',300)
go

create trigger  cat_sub
on cat_tb
after delete,update
as