如何在表和列相同的一行中获得两个不同的值

Question

我正试图让发送消息给其他人和接收消息的用户都排成一行。

UserTable
==================================
userId    userName
-------   ---------
23         Name1
24         Name2
25         Name3

Message Table
==================================================
msgId      senderId       reciverId      messsage
-------    ----------     ----------     -------------
2          24             25              blah
3          25             24              ohh really blah
4          23             24              lets do blah



Output I need

msgId      sender       receiver         message
--------   -------      ----------      ---------
2          Name2         Name3           blah
3          Name3         Name2           Ohh really blah
4          Name1         Name2           lets do blah

那么oracle sql查询应该是什么

Answer 1

只需将UserTable与Message表两次连接即可：

SELECT
    m.msgId,
    u1.userName AS sender,
    u2.userName AS receiver,
    m.message
FROM Message m
INNER JOIN UserTable u1
    ON m.senderId = u1.userId
INNER JOIN UserTable u2
    ON m.reciverId = u2.userId;