sql2000中三个表级联删除
create table a
(
id int primary key,
Content varchar(50)
)
create table b
(
id int primary key,
a_id int
)
create table c
(
id int primary key,
b_id int
)
a,b,c三个表，b表的外键是a表的主键，c表的外键是b表的主键。
删除a中数据，b和c中的相关数据也被删除，这时用触发器
--建立a表的触发器
create trigger dela on a
instead of delete
as
begin
declare @aID int
select @aID=id from deleted
delete from c where b_id in (select id from b where a_id=@aID)
delete from b where a_id=@aID
delete from a where id=@aID
end
删除b表中数据，c中的相关数据也被删除
用外键实现两个表的级联删除
--建立c表外键
alter table c add constraint fk_c_b foreign key (b_id) references b(id) on delete cascade
