将两个表中不相关的列相加，然后根据ID进行联接

Question

我基本上建立了两个这样的表（精简版）：

表1 ：

ID       Amt 1     Amt 2
-------------------------    
112     $20        $30
112     $50        $60
125     $75        $05

表2 ：

ID       Amt 3     Amt 4
-------------------------
112       $25       $30
125       $40       $60
125      $110      $120

所有数量列都需要单独求和，输出类似于以下内容：

查询结果：

ID       Amt 1     Amt 2     Amt 3     Amt 4
--------------------------------------------
112     $70        $90       $25       $30
125     $75        $05       $150      $180

我尝试的联接导致记录重复（和求和）记录是ID在第二张表中重复的次数的一部分。 我没有主键来连接这些表。

任何帮助将不胜感激。

谢谢！

Answer 1

为了正确解决此问题，您需要单独进行聚合。 即使两个表都具有相同ID的多行也可以使用：

select id, sum(amt1), sum(amt2), sum(amt3), sum(amt4)
from ((select id, sum(amt1) as amt1, sum(amt2) as amt2, NULL as amt3, NULL as amt4
       from tbl1
       group by id
      ) union all
      (select id, NULL, NULL, sum(amt3), sum(amt4)
       from tbl2
       group by id
      )
     ) t
group by id

上面的查询给出了一个group by的想法。 为此，有些人希望使用full outer join ：

select coalesce(t1.id, t2.id) as id, amt1, amt2, amt3, amt4
from (select id, sum(amt1) as amt1, sum(amt2) as amt2
       from tbl1
       group by id
      ) t1 full outer join
      (select id, sum(amt3) as amt3, sum(amt4) as amt4
       from tbl2
       group by id
      ) t2
      on t1.id = t2.id

关键是聚合必须在任何联接之前完成，因此您不会有多行的问题。

Answer 2

在SQL Server 2005或更高版本上，您可以使用两个CTE（公用表表达式）对每个表进行求和/分组，然后将两者合并-如下所示：

;WITH CTE1 AS
(
    SELECT 
        ID, Amount1 = SUM(Amt1), Amount2 = SUM(Amt2)
    FROM
        dbo.SumTbl1
    GROUP BY
        ID  
),
CTE2 AS
(
    SELECT 
        ID, Amount3 = SUM(Amt3), Amount4 = SUM(Amt4)
    FROM
        dbo.SumTbl2
    GROUP BY
        ID  
)
SELECT CTE1.ID, Amount1, Amount2, Amount3, Amount4
FROM CTE1
INNER JOIN CTE2 ON CTE1.ID = CTE2.ID

这给了我你想要的输出