Question

我有一个表user_table，如下所示：

USER_TABLE

user1, user2
123    122 
323    323
122    125

我有一个单独的表，用户将用户映射到邮政编码。

user_zip

user zipcode
123    32456
323    12983
121    90878
...

现在我要创建一个这样的表：

user1, user2, user1_zip, user2_zip

我看到我可以通过以下查询获得这样的表格：

select user1, user2, zipcode as user1_zip 
    from user_table as a inner join user_zip as b
    on a.user1 = b.user;

不确定如何映射user2，并再获取一个名为user2_zip的列。

非常感谢你的帮助。

Answer 1

试试这个

SELECT ut.user1, uz1.zipcode AS zip1, ut.user2, uz2.zipcode AS zip2
FROM user_table AS ut
JOIN user_zip AS uz1 ON ut.user1 = uz1.user
JOIN user_zip AS uz2 ON ut.user2 = uz2.user

Answer 2

您可以多次加入同一张桌子：

select u.user1, u.user2, z1.zipcode [user1_zip], z2.zipcode [user2_zip]
from user_table u
join user_zip z1 on z1.user=u.user1
join user_zip z2 on z2.user=u.user2

Answer 3

我会做这样的事情：

with temp as (
select user1 u
from user_table
union
select user2 u
from user_table
)

select u.*, uz.*
from temp
inner join user_zip uz on
temp.u = uz.user

如何使用SQL中的另一个表映射两列？

3 个答案: