SQL查询：具有条件的三列上的SUM

Question

我有一张桌子，上面有这些列：

idx | amount | usercol1 | usercol2 | usercol3 | percentage1 | percentage2 | percentage3

数据通常是这样的：

0   | 1500   | 1        | null     | null     | 100         | null        | null
1   | 3000   | 2        | 3        | null     | 50          | 50          | null

我想对每个用户的数量做一个SUM（）。

范例：

• user1 = 1500 * 100/100（数量* usercol1 / 100）
• user2 = 3000 * 50/100（数量* usercol1 / 100）
• user3 = 3000 * 50/100（数量* usercol2 / 100）

我尝试使用UNION无济于事（未对总和求和）。

有没有办法做到这一点 ？ 问题在于它应该按用户名分组（我在exampletable.usercol1 = usernames.idx上通过左外连接用户名获得）。

我知道这是非标准的，与其他表格的关系会更好。 但是我不允许更改表结构。

非常感谢！ ：=）

在此，给出一个错误结果的示例（似乎仅在中间给出查询的结果）

( 
SELECT SUM(projects.amount * (projects.percentage1/100)) as totalproj, 
entities.idx as idx, 
COUNT(projects.idx) as numproj, 
entities.name 
 FROM projects 
 INNER JOIN entities ON projects.usercol1=entities.idx 
 WHERE projects.usercol1=entities.idx 
GROUP BY name ORDER BY totalproj DESC 
) 
UNION ALL
( 
SELECT SUM(projects.amount * (projects.percentage2/100)) as totalproj, 
entities.idx as idx, 
COUNT(projects.idx) as numproj, 
entities.name 
 FROM projects 
 INNER JOIN entities ON projects.usercol2=entities.idx 
 WHERE projects.usercol2=entities.idx 
GROUP BY name ORDER BY totalproj DESC 
) 
UNION ALL
( 
SELECT SUM(projects.amount * (projects.percentage3/100)) as totalproj, 
entities.idx as idx, 
COUNT(projects.idx) as numproj, 
entities.name 
 FROM projects 
 INNER JOIN entities ON projects.usercol3=entities.idx 
 WHERE projects.usercol3=entities.idx 
GROUP BY name ORDER BY totalproj DESC 
)
ORDER BY totalproj DESC 
LIMIT 10

Answer 1

您可以使用派生表来模拟第一个范式表，然后将其联接到该表上。

SELECT SUM(P.amount * (P.percentage/100)) as totalproj, 
       entities.idx as idx, 
       COUNT(P.idx) as numproj, 
       entities.name 
FROM 
(
SELECT idx, amount, usercol1 AS usercol, percentage1 AS percentage
FROM projects
UNION ALL
SELECT idx, amount, usercol2 AS usercol, percentage2 AS percentage
FROM projects
UNION ALL
SELECT idx, amount, usercol3 AS usercol, percentage3 AS percentage
FROM projects
) P
 INNER JOIN entities ON P.usercol=entities.idx 
 WHERE P.usercol=entities.idx 
 GROUP BY name 
 ORDER BY totalproj DESC 

Answer 2

使用此数据（我添加了一些陌生数据以确保数学正常运行）

0   1500    1   NULL    NULL    100     NULL    NULL
1   3000    2   3       NULL    50      50      NULL
2   780     4   1       3       70      20      50
3   3800    2   4       1       30      20      10

我得到了这些结果

  user  commission
-------  -------------
    1     2036
    2     2640
    3     1890
    4     1306

这是您要找的东西吗？ 以下是我的查询

SELECT  [user]
       ,SUM([commission]) AS commission
FROM    ( SELECT    [usercol1] AS [user]
                   ,( [amount] * [percentage1] ) / 100 AS commission
          FROM      [dbo].[projects]
          WHERE     [usercol1] IS NOT NULL
                    AND [percentage1] IS NOT NULL
          UNION ALL
          SELECT    [usercol2]
                   ,( [amount] * [percentage2] ) / 100
          FROM      [dbo].[projects]
          WHERE     [usercol2] IS NOT NULL
                    AND [percentage2] IS NOT NULL
          UNION ALL
          SELECT    [usercol3]
                   ,( [amount] * [percentage3] ) / 100
          FROM      [dbo].[projects]
          WHERE     [usercol3] IS NOT NULL
                    AND [percentage3] IS NOT NULL
        ) x
GROUP BY [user]