计算折扣

Question

我有这样的客户折扣表：

我有一个名为@Total的deceared varialbe来存储总金额

declare @Total numeric (12,2)

set @Total = (select Sum(LaborAmt) from #Data
              group by Co) 

我需要编写一个查询来根据@Total获取更正后的discountRate。这意味着如果我的总金额是3500000

，它应该返回2

SELECT     dbo.budCustomerDisc.Customer, dbo.budCustDiscRate.DiscountRate
FROM         dbo.budCustDiscRate INNER JOIN
                  dbo.budCustomerDisc ON dbo.budCustDiscRate.DiscountID = dbo.budCustomerDisc.DiscountId AND dbo.budCustDiscRate.JBCo = dbo.budCustomerDisc.JBCo
WHERE     (dbo.budCustomerDisc.Customer = 165) .........

抱歉，我只是不知道要写它

Answer 1

SELECT    budCustomerDisc.Customer, budCustDiscRate.DiscountRate
FROM      budCustDiscRate 
INNER JOIN dbo.budCustomerDisc ON dbo.budCustDiscRate.DiscountID = dbo.budCustomerDisc.DiscountId AND dbo.budCustDiscRate.JBCo = dbo.budCustomerDisc.JBCo
WHERE     budCustomerDisc.Customer = 165 
             And BegBillAmt <= @Total
             And EndBillAmt >= @Total 

Answer 2

这里的关键是，当@Total介于BegBillAmt和EndBillAmt之间时，您正在寻找它返回值。您希望它返回正确的DiscountRate。为此，我们需要BETWEEN语句或两个语句，一个检查BegBillAmt，一个检查EndBill Amt。我将说明两者：

首先使用BETWEEN：

 SELECT     dbo.budCustomerDisc.Customer, dbo.budCustDiscRate.DiscountRate
 FROM         dbo.budCustDiscRate INNER JOIN
              dbo.budCustomerDisc ON dbo.budCustDiscRate.DiscountID = dbo.budCustomerDisc.DiscountId AND dbo.budCustDiscRate.JBCo = dbo.budCustomerDisc.JBCo

 WHERE (dbo.budCustomerDisc.Customer = 165) AND @TOTAL BETWEEN BegBillAmt AND EndBillAmt

有时BETWEEN不清楚（哎呀我不确定它是在SQL Server之外支持的，或者在那种情况下它们是数据库字段而不是静态变量）。所以这里有两个检查：

 SELECT     dbo.budCustomerDisc.Customer, dbo.budCustDiscRate.DiscountRate
 FROM         dbo.budCustDiscRate INNER JOIN
              dbo.budCustomerDisc ON dbo.budCustDiscRate.DiscountID = dbo.budCustomerDisc.DiscountId AND dbo.budCustDiscRate.JBCo = dbo.budCustomerDisc.JBCo


 WHERE  (dbo.budCustomerDisc.Customer = 165) AND BegBillAmt >= @Total AND EndBillAmt <= @Total

希望这有助于为您澄清事情。