Question

我正在尝试在应用具有多个表的左连接时获取行的总和。它似乎正在创建一个结果矩阵，导致错误的求和函数。

示例：

第一张表：客户

第二张表： TotalAssets

第三表： TotalLiability

表格结构：

客户

CustID(int) CustomerName(varchar)
1           Abc
2           Def
3           Ghi

TotalAssets

CustID      Amount
1           2000
1           1000
2           600

TotalLiability

CustID      Amount
1           1000
1           1000
2            800

预期输出

CustID    TotalAssets TotalLiability
1         3000           2000
2          600            800

当前查询

 Select c.CustID , Sum(a.Amount) , Sum(l.Amount) From Customer c
 left join TotalAssests a on a.CustID = c.CustID
 left join TotalLiability l on l.CustID = c.CustID
 Group by c.CustID

这个当前查询的问题是总和不正确，因为我认为第一个左连接创建了一个包含多个记录的第一个集合，然后应用了第二个。

感谢任何帮助

更新

我通过以下方法找到了一些运气，但它似乎是一个糟糕/ hacky选项，因为在我的情况下，我在组中有超过7-8个元素，并添加更多左子句导致查询难以管理。

新查询导致了正确的结果，但看起来很难维护

 Select Set1.CustID , Set1.TotalAssets, Sum(l.Amount) from (Select c.CustID , Sum(a.Amount) as TotalAssets From  Customer c
 left join TotalAssests a on a.CustID = c.CustID
 Group by c.CustID)Set1
 left join TotalLiability l on l.CustID = Set1.CustID.
 Group by Set1.CustID , Set1.TotalAssets

Answer 1

我认为这会以最小的复杂性为您提供您想要的东西：

select c.CustId, isnull(a.Amount, 0) as TotalAssets, isnull(l.Amount, 0) as TotalLiability
from Customers c
left join (
    select CustId, sum(Amount) as Amount from TotalAssets group by CustId
) a on a.CustId = c.CustId
left join (
    select CustId, sum(Amount) as Amount from TotalLiability group by CustId
) l on l.CustId = c.CustId

您需要分别对两个表进行分组/求和，因为它们中的数据是独立的。左连接到customers表确保仍然报告在两个/两个表中都没有条目的客户。

Answer 2

这应该有效：

Select c.CustID 
, (select sum(a.amount) from TotalAssests a where a.CustId = c.CustID) as SumAsset
, (select Sum(l.Amount) TotalLiability l where l.CustID = c.CustID) as SumLiability
From Customer c

Answer 3

希望以下工作减少维护，

DECLARE @Customer TABLE (CustID int, CustomerName varchar(50)) DECLARE @TotalAssets TABLE (CustID int, Amount INT) DECLARE @TotalLiability TABLE (CustID int, Amount INT)
INSERT INTO @Customer
SELECT 1,
       'ABC'
UNION
SELECT 2,
       'DEF'
UNION
SELECT 3,
       'GHI'

 --Select * From @Customer

INSERT INTO @TotalAssets
SELECT 1,
       2000
UNION
SELECT 1,
       1000
UNION
SELECT 2,
       600 

--Select * From @TotalAssets

INSERT INTO @TotalLiability
SELECT 1,
       1000
UNION
SELECT 1,
       1000
UNION
SELECT 2,
       800 

--Select * From @TotalLiability

SELECT *
FROM @Customer
SELECT C.CustID,
       C.CustomerName,
       Sum(A.Amount) TotalAssets,
       Sum(L.Amount) TotalLiability
FROM @Customer C
JOIN @TotalAssets A ON C.CustID = A.CustID
JOIN @TotalLiability L ON C.CustId = L.CustID
GROUP BY C.CustID,
         C.CustomerName

使用多于1个表的Sum Clause左连接会给出不正确的Sum

3 个答案: