Question

我遇到问题，当我查询sql server以检索来自不同三个表的记录时，它执行SUM([Bills.Extrabill_dollar])和SUM([Receipts.Amount])的完全错误的值，下面是我的查询，请帮助我。

select Customers.SNO, SUM(Bills.Extrabill_dollar) as [ExtraAmount],SUM(Receipts.Amount) as [Received]
from
Customers left join Bills on Customers.SNO=Bills.CustomerSNO
left join Receipts on Customers.SNO=Receipts.CSNO
group by Customers.SNO

但如果我使用两个单独的查询来返回 SUM（Extra_dollar）和 SUM（Extra_dollar）
SELECT Bills.CustomerSNO as [CustomerSNO], SUM(Bills.Extrabill_dollar) AS [TotalExtraAmount] from Bills group by Bills.CustomerSNO

SELECT Receipts.CSNO as [CustomerSNO], SUM(Receipts.Amount) AS [TotalReveied] from Receipts group by Receipts.CSNO如果使用 JOIN 合并这些表格，将会返回正确的结果，不会返回，请帮助我亲爱的。

Answer 1

说你的答案不正确，我不知道。

我认为既然您正在使用LEFT JOIN，那么可能会导致问题。左连接从客户获取所有值，甚至会出现不匹配的行，这些行将被映射到Bills and Receipts下的NULL值。

您可以使用此代码进行试用。

SELECT Customers.SNO
, SUM(Bills.Extrabill_dollar) AS [ExtraAmount]
, SUM(Receipts.Amount) AS [Received]
FROM
Customers INNER JOIN Bills 
ON Customers.SNO=Bills.CustomerSNO
INNER JOIN Receipts 
ON Customers.SNO=Receipts.CSNO
GROUP BY Customers.SNO

Answer 2

select Customers.SNO, SUM(Bills.Extrabill_dollar) as [ExtraAmount],SUM(Receipts.Amount) as [Received]
from
Customers right join Bills on Customers.SNO=Bills.CustomerSNO
right join Receipts on Customers.SNO=Receipts.CSNO
group by Customers.SNO

Answer 3

亲爱的，感谢您的帮助，经过漫长的旅程，我找到了答案：

select c.SNO, c.CName, 
isnull((select SUM(PricePerKwt_dollar) from Bills
where Bills.CustomerSNO =c.SNO),0.00) as [TotalBills],
isnull((select SUM(Receipts.Amount) from Receipts
where Receipts.CSNO = c.SNO),0.00) as [TotalReceipts]
 from Customers c

我的连接查询返回了正确的值

3 个答案: