Question

我正在尝试完成以下操作，我不确定是否可行。我有一个SELECT语句，其中包含两个表列的内部SELECT，如下所示：

SELECT 
col1,
col2,

   (SELECT SUM(col1)
    FROM table2)
    AS FirstResultToAdd,

   (SELECT SUM(col2)
    FROM table3)
    AS SecondResultToAdd,

FROM Table1

所以我的问题是：是否可以执行计算，例如执行SUM＆＃34; FirstResultToAdd＆＃34;和＆＃34; SecondResultToAdd，并将其作为单个列结果返回到＆＃34; Table1＆＃34;？另外要记住，我已经排除了表的任何连接以保持示例简单。

Answer 1

我相信你想对Sub-query

的结果执行一些逻辑

添加两个sub-query结果

SELECT col1, 
       col2,

      (SELECT col1 
       FROM table2)   
       AS FirstResultToAdd, 

      (SELECT col2 
       FROM table3)   
       AS SecondResultToAdd, 

      (SELECT col1 
       FROM table2) 
       + 
      (SELECT col2 
       FROM table3) 
       AS total 
       FROM table1

为了使查询更具可读性，您可以将原始查询设为Sub-Select并执行Outer query

中的逻辑

Answer 2

再嵌套一次......

select col1, col2, sum( FirstResultToAdd )
from (
SELECT 
col1,
col2,

   (SELECT col1
    FROM table2)
    AS FirstResultToAdd,

   (SELECT col2
    FROM table3)
    AS SecondResultToAdd,

FROM Table1
)

Answer 3

修改：固定分组

试试这个：

 Select     A.Col1,
            A.Col2,
           (B.Col3 + C.Col4)

From(
        (Select Col1,
                Col2
         From   [Table1]) A

        Inner join (Select  Sum(Col3) AS Col3
        From    [Table2]) B on 1 = 1

        Inner join (Select  Sum(Col4) AS Col4
        From    [Table3]) C on 1 = 1
     )
Group By  A.Col1,
          A.Col2,
          B.Col3,
          C.Col4

在SQL中我可以在多列上执行逻辑，这是SELECT语句吗？

3 个答案: