检查 2 个用户是否与 mySQL 在同一个房间 [英] Check if 2 users are in the same room with mySQL

问题描述

我有一张 user_to_room 表

I have a user_to_room table

roomID | userID 

我现在想检查一下，是否有 2 个用户在同一个房间

I now want to check, if 2 users are in the same room

SELECT roomID
FROM   room_to_user
WHERE  userID = 1 AND 2

如何通过 JOIN 实现这一点?

How to achieve this with a JOIN?

推荐答案

进行自连接:

SELECT DISTINCT u1.roomID AS roomID
FROM   user_to_room u1, user_to_room u2
WHERE  u1.userID = 1 AND u2.userID = 2
AND    u1.roomID = u2.roomID;

请参阅演示.

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