Question

我有一个包含三列id的表，follower_id，following_id，我只有一个 101 或 105 的ID现在我想要记录{{1}跟随user1和user2关注一个查询中的user2 。

表格结构

user1

结果应为1 - ＆gt; 101-> 105或3-> 105-> 101

Answer 1

如果您想要跟随者和跟随匹配的行，您可以使用自我加入

select t1.* from my_table as t1
inner  join my_table as t2 
where t1.follower_id = t2.following_id
and  t1.following_id = t2.follower_id

Answer 2

您可以使用least和greatest来执行此操作。

select * from t
where (least(follower_id,following_id),greatest(follower_id,following_id))
in (select least(follower_id,following_id),greatest(follower_id,following_id)
    from t
    group by least(follower_id,following_id),greatest(follower_id,following_id)
    having count(*) > 1)

Answer 3

可能是这个查询会帮助你......

SELECT *
FROM Yourtable A
WHERE EXISTS (SELECT 1 FROM Yourtable B WHERE B.follower = A.following)
AND EXISTS (SELECT 1 FROM Yourtable C WHERE C.following = A.follower)

如何使用单个查询获取记录

3 个答案: