数据库级联删除．

 create table c
(
 id varchar(20) primary key,
 password varchar(20) not null
)
create table d
(
 
 id int identity(1,1) primary key,
 name varchar(20) not null,
 userid varchar(20),
 foreign key(userid) references c(id) on delete cascade
)
insert c values ('11','aaa')
insert c values('23','aaa')
insert d values('da','11')
insert d values('das','11')
insert d values('ww','23')
delete c where id='11'