MySQL 中的两个左连接和一个并集
我正在尝试在 MySQL 中执行一个相当复杂的查询；至少对我来说很复杂。
这是我正在尝试执行的操作的示例：
SELECT * FROM friends
LEFT JOIN users ON users.uid = friends.fid1
LEFT JOIN users ON users.uid = friends.fid2
WHERE (friends.fid1 = 1) AND (friends.fid2 > 1)
UNION SELECT fid2 FROM friends
WHERE (friends.fid2 = 1) AND (friends.fid1 < 1)
ORDER BY RAND()
LIMIT 6;
我正在返回：ERROR 1066 (42000): Not unique table/alias: 'users'。
我哪里出错了，我应该如何执行这个查询？
I'm trying to do a pretty complex query in MySQL; complex for me, at least.
Here's an example of what I'm trying to do:
SELECT * FROM friends
LEFT JOIN users ON users.uid = friends.fid1
LEFT JOIN users ON users.uid = friends.fid2
WHERE (friends.fid1 = 1) AND (friends.fid2 > 1)
UNION SELECT fid2 FROM friends
WHERE (friends.fid2 = 1) AND (friends.fid1 < 1)
ORDER BY RAND()
LIMIT 6;
I'm getting back: ERROR 1066 (42000): Not unique table/alias: 'users'.
Where am I going wrong, and how should I really be performing this query?
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为您的表命名，例如：
Alias your table, like:
您已经使用表的不同字段编写了两次左连接，似乎当它被解析时，给它们别名，然后将它们与
friends表连接You have written left join two times with different fields of tables, it seems to When it got parse so give them alias and then join them with
friendsTable