SQL获取不是我的朋友的朋友的所有朋友 [英] Sql to get all the friends of friends who's not my friend

问题描述

我正在研究可能的朋友"功能.我需要向所有不是我的朋友的朋友显示所有朋友，也不要向我发送或没有我的待处理请求

I'm working on a "Possible Friends" feature. where i need to show all the friends of friends who's not my friend and also not send me or not having my pending request

FRIENDSHIPS
user_id
friend_id
status  (0 = pending, 1 = approved) 

对于每一次友谊，我都会做两个记录.假设用户1和2成为朋友...我要在friendships表中记录一个where user_id=1,friend_id=2和另一个where user_id=2, friend_id=1.

For each friendship I make two records. Say users 1 and 2 become friends... I would make a record where user_id=1,friend_id=2 and another where user_id=2, friend_id=1 in the friendships table.

当第一个用户发送请求时，将状态设置为0，当朋友接受请求时，我将两行都更新为1

when first user send request, set status to 0 and when friend accept request then I would update both row with 1

我将如何基于我的朋友的朋友进行一个建议可能的朋友"的sql查询?

How would I make a sql query that suggests "possible friends" based on friends of my friends ?

推荐答案

在这里，您可以...简单加入

Here you go... simple join

SELECT F2.friend_id
FROM FRIENDSHIPS F
JOIN FRIENDSHIPS F2 ON F.friend_id = F2.user_id
WHERE F2.friend_id NOT IN (SELECT friend_ID FROM FRIENDSHIPS WHERE user_id = @user_id)
  AND F.user_id = @user_id

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