Question

您好我有一个查询，它返回两行数据作为计数。我想找到列值的总和。我的sql：

(SELECT count(memberid) count 
   FROM `friendRequest`, Member 
   where status = 2 and memberid = sender and receiver = 19) 
UNION 
(SELECT count(memberid) count 
   FROM `friendRequest`, Member 
   where status = 2 and memberid = receiver and sender = 19)

我尝试过使用Select Sum（我的上面的查询）但是我收到了错误。有人可以帮帮我吗。我只需要一些上述值。

此致的Pankaj

Answer 1

可以在一个查询中抓取两个结果集：

SELECT count(memberid) count 
FROM `friendRequest`, Member 
WHERE status = 2 AND (
    (memberid = sender AND receiver = 19) OR 
    (memderid = receiver AND sender = 19)
)

Answer 2

尝试：

SELECT SUM(count)
FROM
  ...the rest of your query...

Answer 3

如果您要使用聚合，则需要使用GROUP BY

对其进行分组

(SELECT count(memberid) SUM(count) 
   FROM `friendRequest`, Member 
   where status = 2 and memberid = sender and receiver = 19
   GROUP BY Member) 
UNION 
(SELECT count(memberid) SUM(count) 
   FROM `friendRequest`, Member 
   where status = 2 and memberid = receiver and sender = 19
   GROUP BY Member)

Answer 4

以下应该按原样运作

SELECT SUM(count)
FROM   (
         (SELECT count(memberid) count 
          FROM `friendRequest`, Member 
          where status = 2 and memberid = sender and receiver = 19) 
          UNION 
         (SELECT count(memberid) count 
          FROM `friendRequest`, Member 
          where status = 2 and memberid = receiver and sender = 19)
       ) AS anyAliasWillDo

但我强烈建议您停止使用隐式连接（过时）并开始使用显式连接语法。然后声明变成

SELECT SUM(COUNT)
FROM   (
            SELECT  COUNT(memberid) AS COUNT 
            FROM    `friendRequest` AS fr
                    INNER JOIN Member AS m ON m.memberid = fr.sender
            WHERE   status = 2 AND receiver = 19 
            UNION ALL
            SELECT  COUNT(memberid) AS COUNT 
            FROM   `friendRequest` AS fr 
                    INNER JOIN Member AS m ON m.memberid = fr.receiver
            WHERE   status = 2 AND sender = 19
        ) AS AnyAliasWillDo

查找从查询中找到的值的总和

4 个答案: