Question

我有一个我试图在DatasetAdapter中创建的SQL，它在某一点上起作用，但我不知道最后一点是否正常工作。

我有一个表（MainTable），其中包含以下字段：ID Name Image Area Mean

我想计算ABS(Area-?) AS Cal1, ABS(Mean-?) AS Cal2 , Cal1+Cal2 As Cal3

SELECT 
ID, Image, Name, Area, Mean, ABS(Area - ?) AS cal1, ABS(Mean - ?) AS cal2, Cal1+Cal2 AS cal3
FROM  MainTable

我想获得Cal3的最大值

SELECT        MAX(cal3) AS maxofcal3
FROM          
  (SELECT        ID, Image, Name, Area, Mean, ABS(Area - ?) AS cal1, ABS(Mean - ?) AS cal2, derivedtbl_1.cal1 + derivedtbl_1.cal2 AS cal3
FROM            MainTable) 
derivedtbl_1

它到目前为止给我的最大值为cal3。

问题：我想进行另一次计算（Cal3 / maxofcal3）。我弄清楚了。我尝试了下面的代码，但却出现了一个错误：

SELECT        MAX(Cal3) AS maxofCal3, Cal3 / MaxofCal3 AS Norm
FROM            (SELECT        ID, Image, Name, Area, Mean, ABS(Area - ?) AS cal1, ABS(Mean - ?) AS cal2, derivedtbl_1.cal1 + derivedtbl_1.cal2 AS cal3
                                                    derivedtbl_1.Cal1 + derivedtbl_1.Cal2 AS Cal3
                          FROM            MainTable) derivedtbl_1
GROUP BY Cal3 / MaxofCal3.

Answer 1

仅按Cal4分组，而不是按Cal4 / MaxofCal4分组

请查看以下示例，了解如何使代码正常工作：

CREATE TABLE #SampleTable (ID int, Image nvarchar(10), Name nvarchar(10), Area int, Mean int )


SELECT MAX(Cal3) AS maxofCal3, Cal4 / MAX(Cal3) AS Norm
FROM (
SELECT ID, Image, Name, Area, Mean, ABS(Area - 1) AS cal1, ABS(Mean - 1) AS cal2, ABS(Area - 1) + ABS(Area - 1) AS cal3, ABS(Area - 1) + ABS(Area - 1) AS Cal4 FROM #SampleTable
) derivedtbl_1 
GROUP BY Cal4


DROP TABLE #SampleTable

SELECT语句中的计算错误

1 个答案: