[英]Twitter style following-follower table in SQL
I have a basic follower/following table in mySQL which looks like this. 我在mySQL中有一个基本的关注者/关注表,看起来像这样。
id user_id follower_id
1 userA userB
2 userC userA
3 userA userC
4 userB userC
5 userB userA
I checked these topics but couldnt find what I need 我检查了这些主题,但无法找到我需要的东西
database design for 'followers' and 'followings'? “追随者”和“追随者”的数据库设计?
SQL Following and Followers SQL关注者和关注者
What I need is to have a system like this: 我需要的是拥有这样一个系统:
Assume we are userB ( we follow userA, we are followed by userC and userA) 假设我们是userB(我们关注userA,接下来是userC和userA)
I like to return a result that includes this follower/following state. 我想返回包含此关注者/关注状态的结果。 For example for userB: 例如对于userB:
id followedBy areWeFollowing
1 userA 1
2 userC 0
Thanks for your help! 谢谢你的帮助!
arda 阿尔达
With this query to find if who you follow, follow you too. 通过此查询查找您关注的人,也可以关注您。
SELECT ff1.follower_id as followedBy,
(
select count(follower_id)
from follower_following as ff2
where ff2.user_id = ff1.follower_id
and ff2.follower_id = ff1.user_id
) as areWeFollowing
FROM follower_following as ff1
where user_id = 'userB';
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