SELECT DISTINCT總和的SQL Server

Question

我與SUM（tblReview.GradePoint）我得到6的結果爲羣ID金球獎，因爲我有三個產品羣ID巴隆一個問題，但我希望得到的結果是2，因爲只有一個在tblReview該組ID，我怎麼能做到這一點嗎？

SELECT  Product.GroupID, 
      max(Product.ProductID) as ProductID, 
      max (Product.BrandID) as BrandID, 
      max (Product.Year) as Year, 
      max (Product.Name) as Name, 
      max (tblBrand.BrandName)as BrandName, 
      SUM(tblReview.GradePoint) as GradePoint 

FROM  Product INNER JOIN 
      tblBrand ON Product.BrandID = tblBrand.BrandID LEFT OUTER JOIN 
      tblReview ON Product.GroupID = tblReview.GroupID 

GROUP BY Product.GroupID 


HAVING COUNT(distinct Product.GroupID) = 1 

ORDER BY GradePoint DESC 

Product 
ProductID GroupID  BrandID 
-------------------------------------- 
1   Ballon  10 
2   Ballon  10 
3   Ballon  10 
4   Ball  21 
5   Ball  21 
6   Chess  2 
7   Chess  2 
8   Hat   30 


tblReview  
ProductID GroupID  GradePoint 
------------------------------------------ 
2   Ballon  2 
4   Ball  1 
5   Ball  1 
5   Ball  1 
6   Chess  -1 
8   Hat  1 


tblBrand  
BrandID  ProductID 
----------------------- 
10   1 
10   2 
10   3 
21   4 
21   5 
2   6 
2   7 
30   8 

Answer 1

試試這個：

SELECT  Product.GroupID, 
      max(Product.ProductID) as ProductID, 
      max (Product.BrandID) as BrandID, 
      max (Product.Year) as Year, 
      max (Product.Name) as Name, 
      max (tblBrand.BrandName)as BrandName, 
      max(tblReview.GradePoint) as GradePoint 

FROM  Product INNER JOIN 
      tblBrand ON Product.BrandID = tblBrand.BrandID LEFT OUTER JOIN 
      (SELECT GroupID, SUM(GradePoint) GradePoint FROM tblReview GROUP BY GroupID) tblReview ON Product.GroupID = tblReview.GroupID 

GROUP BY Product.GroupID