Question

我有一个相当复杂的SQL语句，我正在尝试编写，而不知道该怎么做。

基本上，我正在寻找聊天室中最活跃的人（我的聊天存储在SQL表中），但是减去他们说特定消息TIMES乘以减法的乘数的次数。

这是“基本”查询，可以很好地找出有人聊天的频率：

SELECT users.name, count(*) as count1, users.flag2, users.flag1
            FROM chat
            INNER JOIN users
            ON chat.userid=users.id
            WHERE channel=$channel
            GROUP BY userid
            ORDER BY count DESC
            LIMIT 100;

此查询会告诉我用户说出我想要减去的的特定消息的次数：

SELECT userid, count(*) as count2 FROM chat WHERE channel=$channel AND text = '[some message]' GROUP BY userid

我正在寻找的是第一个让“count”实际上等于“ count1 - count2 * 10 ”的查询。我有一个相当艰难的时间来弄清楚如何将这两个查询组合成一个。我将使用生成的“值”作为ORDER BY / LIMIT子句，所以我需要SQL来实际执行此计算而不是在多个查询中执行...

Answer 1

   SELECT T1.name,(count1 - 10* COALESCE( count2,0) ) as NetCount
   FROM
    (
            SELECT userid,users.name, count(*) as count1
            FROM chat
            INNER JOIN users
            ON chat.userid=users.id
            WHERE channel=$channel
            GROUP BY userid,users.name
            ORDER BY count DESC
            LIMIT 100;
     ) as T1

  LEFT JOIN

  (
            SELECT userid, count(*) as count2
            FROM chat
            WHERE channel=$channel AND text = '[some message]'
            GROUP BY userid
  ) as T2

  ON T1.userid=T2.userid

SQL减去两个独立的计数

1 个答案: