一列中的SQL MAX和MIN

Question

我在获取最大值和最小值时遇到问题，我希望结果为XXL和XXS

  SELECT MAX(tblSizeXL.SizeXLName) AS maxSize, 
         MIN(tblSizeXL.SizeXLName) AS minSize    
    FROM Product 
    JOIN tblSizeXL ON Product.SizeXLID = tblSizeXL.SizeXLID
   WHERE (Product.GroupID = @GroupID)
GROUP BY tblSizeXL.SizeXLID
ORDER BY tblSizeXL.SizeXLID DESC

tblSize

SizeXLID     SizeXLName
-----------------------
1            XXS
2            XS
3            S
4            M
5            L
6            XL
7            XXL
8            XXXL

Answer 1

您将必须进行内部查询才能获取所需的数据：

SELECT max.SizeXLName as maxSize, min.SizeXLName as minSize
  FROM 
  (SELECT MAX(tblSizeXL.SizeXLID) as MaxSizeXLID, MIN(tblSizeXL.SizeXLID) as MinSizeXLID
     FROM Product
     JOIN tblSizeXL ON Product.SizeXLID = tblSizeXL.SizeXLID
    WHERE Product..GroupID = @GroupID) base
  JOIN tblSizeXL max ON max.SizeXLID = base.MaxSizeXLID
  JOIN tblSizeXL min on min.SizeXLID = base.MinSizeXLID

Answer 2

删除group by子句，您的查询就可以了。