MySQL Multiple INNER JOIN + GROUP BY 未按预期工作

Question

我正在根据一些字段值生成会员排行榜。使用下面的 SQL 我正在获取这些值...

SELECT ue1.user_id, 
   ue1.meta_value coins ,
   ue3.meta_value user_rank ,
   ue2.meta_value gems,
   COUNT(ue4.user_id) quiz_count,
   COUNT(ue5.user_id) video_watch_count,
   ue1.meta_value + ue3.meta_value + ue2.meta_value total_points

   FROM `wp_usermeta` as ue1

   INNER JOIN `wp_usermeta` as ue2 ON ue2.user_id = ue1.user_id
     AND ue1.meta_key = '_coin_points' 
     AND ue2.meta_key = '_gem_points'

  INNER JOIN `wp_usermeta` as ue3 ON ue3.user_id = ue1.user_id
     AND ue3.meta_key = '_user_rank'

  INNER JOIN `wp_gamipress_user_earnings` as ue4 ON ue4.user_id = ue1.user_id
    AND ue4.post_type = 'quiz-game-master'

  INNER JOIN `wp_gamipress_user_earnings` as ue5 ON ue5.user_id = ue1.user_id
     AND ue5.post_type = 'video-game-master'

  WHERE ue1.meta_value > 0 

  AND   ue2.meta_value > 0 

  GROUP BY ue1.user_id, ue1.meta_value, ue2.meta_value, ue3.meta_value, ue4.user_id, ue5.user_id

  ORDER BY total_points DESC LIMIT 0, 50

我得到的是......不是预期的查询结果

看到了吗？ video_watch_count 正在复制 quiz_count 值。我不知道为什么？如果您能在这里帮助我，将不胜感激。

Answer 1

检查您的加入声明。对于quiz_count, video_watch_count,，您从表wp_gamipress_user_earnings 中选择数据。对于每个条目，如果满足连接条件，它将从相应的表中返回user_id。

最后你使用user_id 对它进行分组，这对两个连接结果都是通用的。这就是你得到相同计数的原因。