TSQL更新查询意外行为

Question

我有一个嵌套的选择查询返回适量的行。该查询构建一个记录集并将其与一个表进行比较，并返回查询中不在表中的记录。

我将选择查询转换为更新查询。我正在试图用查询返回的行填充表。当我运行更新查询时，它返回零行更新。我不明白为什么，因为选择查询返回记录，我在更新查询中使用相同的代码。

感谢

选择查询：（这是返回几条记录）

Select * 
From 
(SELECT DISTINCT 
ProductClass,SalProductClass.[Description],B.Branch,B.BranchDesc,B.Salesperson,B.Name, 
CAST(0 AS FLOAT) AS Rate,'N' AS Split 
FROM (SELECT SalBranch.Branch,SalBranch.[Description] AS BranchDesc,A.Salesperson,A.Name 
     FROM (SELECT DISTINCT 
      Salesperson,Name 
      FROM SalSalesperson 
      ) A 
     CROSS JOIN SalBranch 
    ) B 
CROSS JOIN SalProductClass 
) C 
Left Outer Join RateComm On 
RateComm.ProductClass = C.ProductClass and 
RateComm.Branch = C.Branch And RateComm.Salesperson = C.Salesperson 
Where RateComm.ProductClass is Null 

更新查询：（这是返回零个记录）

UPDATE RateComm 
SET RateComm.ProductClass=C.ProductClass,RateComm.ProdClassDesc=C.ProdClassDesc, 
RateComm.Branch=C.Branch,RateComm.BranchDesc=C.BranchDesc,RateComm.Salesperson=C.Salesperson, 
RateComm.Name=C.Name,RateComm.Rate=C.Rate,RateComm.Split=C.Split 
    FROM (SELECT DISTINCT 
      ProductClass,SalProductClass.[Description] AS ProdClassDesc,B.Branch,B.BranchDesc,B.Salesperson,B.Name, 
      CAST(0 AS FLOAT) AS Rate,'N' AS Split 
      FROM (SELECT SalBranch.Branch,SalBranch.[Description] AS BranchDesc,A.Salesperson,A.Name 
       FROM (SELECT DISTINCT 
         Salesperson,Name 
         FROM SalSalesperson 
        ) A 
       CROSS JOIN SalBranch 
       ) B 
      CROSS JOIN SalProductClass 
     ) C 
    LEFT OUTER JOIN RateComm ON C.ProductClass=RateComm.ProductClass AND 
    C.Salesperson=RateComm.Salesperson AND C.Branch=RateComm.Branch 
    WHERE RateComm.ProductClass IS NULL 

Answer 1

这很难更新的内容没有按”不存在。您是否尝试过使用INSERT查询？