Mysql Sql计数返回错误的数字

我有一个api，我调用它，我需要来自不同表的大量数据，所以我对它们使用联接，现在的问题是，虽然我有4个回复，5个交互，但数据总是返回20个回复和20个交互，这就是结果：

screen_name screen_state replies interactions alerts
sjerd       0            20      20           0

我使用此查询统计记录和结果：

   SELECT u.screen_name,
          u.screen_state,
          count(r.id) AS replies,
          count(i.id) AS interactions,
          count(a.alerts) AS alerts
   FROM   users u 
   LEFT   JOIN reply r ON u.id = r.user 
   LEFT   JOIN interactions i ON u.id = i.user_id 
   LEFT   JOIN alerts a ON u.id = a.user_id WHERE u.id ='2' 
   GROUP  BY u.id, u.screen_state

有人知道为什么回复表中总共只有7行回复，却返回了20行吗， 交互表中共有5行交互。

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每行是1个反应或回复

由于所有表都在同一级别上联接，因此您的计数总是会给出相同的结果

您需要将计数作为内联子查询（或其他什么-我永远记不起正确的术语）：

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谢谢，这就成功了。您知道如果我不添加distinct，为什么它会返回比表中更多的行吗？不客气，请将r.id、i.id、a.alerts添加到您的查询中。查看结果集（暂时删除组）。

SELECT u.screen_name,
       u.screen_state,
       (select count(*) from reply r where u.id = r.user) AS replies,
       (select count(*) from interactions i where u.id = i.user_id) AS interactions,
       (select count(*) from alerts a where u.id = a.user_id) AS alerts
FROM   users u
WHERE u.id ='2' 

   SELECT u.screen_name, u.screen_state, 
   count(DISTINCT r.id) AS replies,
   count(DISTINCT i.id) AS interactions,
   count(DISTINCT a.alerts) AS alerts 
   FROM users u 
   LEFT JOIN reply r ON u.id = r.user 
   LEFT JOIN interactions i ON u.id = i.user_id 
   LEFT JOIN alerts a ON u.id = a.user_id WHERE u.id ='2' 
   GROUP BY u.id, u.screen_state