连接两个表，多行到单行不同列

Question

我有两个table。

USER

USER_ID | USER_NAME
--------------------
659    |  John  
660    |  Andrew 
661    |  Bianca
--------------------

USER_ADDRESS

USER_ID |TYPE |    ADDRESS
------------------------------
659     | HOME |    New York
659     | WORK |    New Jersey
660     | HOME |    San Francisco
660     | WORK |    Fremont
------------------------------

我想将第 2 个 table 的多条记录合并到第 1 个 table 的单行中。

USER_ID | USER_NAME | HOME_ADDRESS | WORK_ADDRESS 
--------------------------------------------------
659   |  John    |   New York      | New Jersey
660   |  Andrew  |   San Francisco | Fremont

如何在 select 查询中获得上述输出？

Answer 1

试试这个：

SELECT u.*, uah.address as home_address, uaw.address as work_address
FROM users u
LEFT OUTER JOIN user_address uah
    ON u.user_id = uah.user_id
    AND uah.type = 'HOME'
LEFT OUTER JOIN user_address uaw
    ON u.user_id = uaw.user_id
    AND uaw.type = 'WORK'

连接两个表，多行到单行不同列

Joining two tables, multiple rows into a single row different columns

sql

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