如何讓朋友誰喜歡我的話題

Question

我有用戶表 有ID場 和友誼表frienduser有friend1id或friend2id，根據誰發送給誰第一 和喜歡的請求表| | THREAD_ID - 用戶ID 我想從用戶選擇誰是我的朋友的人，喜歡的話題

Answer 1

這醜陋的部分是frienduser表既可以鏈接的事實ID。我認爲解決這個問題的最簡單方法就是與工會組織在一起。

/* Case 1: My ID is friend1id, my friend is friend2id */ 
select u2.* 
    from users u1 
     inner join frienduser f 
      on u1.id = f.friend1id 
     inner join users u2 
      on f.friend2id = u2.id 
     inner join likes l 
      on u2.id = l.userid 
    where u1.id = @MyUserId 
     and l.threadid = @MyThreadId 
union 
/* Case 2: My ID is friend2id, my friend is friend1id */ 
select u2.* 
    from users u1 
     inner join frienduser f 
      on u1.id = f.friend2id 
     inner join users u2 
      on f.friend1id = u2.id 
     inner join likes l 
      on u2.id = l.userid 
    where u1.id = @MyUserId 
     and l.threadid = @MyThreadId 

Answer 2

There you go.