省市区3表查询

[ld191474639]

根据选择的省，来查询出市区

create table province(
id int identity(1,1) primary key,
pname varchar(20)
)
create table citys(
cid int identity(1,1) primary key,
cname varchar(20),
cpid int constraint cp_id references province(id) 
)
create table district(
did int identity(1,1) primary key,
dname varchar(20),
cdid int constraint cd_id references citys(cid) 
)

[昵称被占用了]

市查询 select * from citys where pid = 1 区查询 select * from district where cdid in ( select cid from citys where pid = 1 )

[ld191474639]

不是啊，只写一条语句查询出市区

[發糞塗牆]

搞点数据来看看