如何编写MySQL Join查询 [英] How to write a MySQL Join query

问题描述

我有两个桌子.

users: 
       uid | city     | username | flag |
       10  | New York | john     | 1    |
       14  | Tokyo    | kawasaki | 1    |
       15  | Tokyo    | coder    | 1    |

groupmember: 
       id  | uid  | groupid  |
       1   | 10   | 16       |
       2   | 14   | 16       |
       3   | 15   | 21       |

两个表中的'uid'相同.

我想选择在城市东京"中的所有用户，这些用户也在组ID为"16"的组中.

I want to select all users who are in city "tokyo" who are also in the group with groupid "16" .

在这种情况下，查询结果应该为

So the query resutl should be (in this case)

14  | Tokyo    | kawasaki | 1    |

推荐答案

SELECT u.uid, u.city, u.username, u.flag 
FROM users u
JOIN groupmember g ON u.uid = g.uid
WHERE u.city = 'Tokyo'
  AND g.groupid = 16;

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