中位数计算不正确

Question

我已经尝试了所有可能的方法来计算特定列的中值，但一直得到与 Excel 不同的值。

我正在研究 SQL2008R2

这是我迄今为止尝试过的方法：

SELECT  Entity,
                BillPeriod,
                Cost,
                PatientDays,
                0 AS Median
        FROM GroupCTE
        UNION 
        SELECT  Entity,
                BillPeriod,
                Cost,
                PatientDays,
                0 AS Median
        FROM RegionCTE
                    UNION 
        SELECT  Entity,
                BillPeriod,
                Cost,
                PatientDays,
                0 AS Median
        FROM InstitutionCTE
        Union
        SELECT  'Median' as Entity,
                BillPeriod,
                0 as Cost,
                0 as PatientDays,
                (((
                    (SELECT MAX(Cost) FROM
                        (SELECT TOP 50 PERCENT Cost FROM InstitutionCTE WHERE Cost <> 0 ORDER BY Cost ASC) AS BottomHalf)
                    +
                    (SELECT MIN(Cost) FROM
                        (SELECT TOP 50 PERCENT Cost FROM InstitutionCTE WHERE Cost <> 0 ORDER BY Cost DESC) AS TopHalf)
                )) / 2)  AS Median

我是不是做错了什么？

我试过了：Function to Calculate Median in Sql Server

谢谢

Answer 1

所以我设法解决了这个问题。问题是，出于某种原因，进行中值计算给出的结果与 Excels 中值函数的结果不同。

我创建了一个 TEMP table 并导入了 UNION 的结果，然后使用我的计算更新了 Median 列：

INSERT INTO #Temp
            SELECT  Entity,
                    BillPeriod,
                    ((Cost) / (PatientDays)) * 100 AS Cost,
                    PatientDays,
                    0 AS Median
            FROM GroupCTE
            UNION 
            SELECT  Entity,
                    BillPeriod,
                    ((Cost) / (PatientDays)) * 100 AS Cost,
                    PatientDays,
                    0 AS Median
            FROM RegionCTE
            UNION 
            SELECT  Entity,
                    BillPeriod,
                    ((Cost) / (PatientDays)) * 100 AS Cost,
                    PatientDays,
                    0 AS Median
            FROM InstitutionCTE
            UNION       
            SELECT  'Median' as Entity,
                    BillPeriod,
                    0 AS Cost,
                    0 AS PatientDays,
                    0 AS Median


            FROM InstitutionCTE
            GROUP BY Entity, BillPeriod, PatientDays

            UPDATE #Temp
            SET Median =    ((
                        ((SELECT MAX(Cost) FROM
                            (SELECT TOP 50 PERCENT Cost FROM #Temp WHERE Cost <> 0 ORDER BY Cost ASC) AS BottomHalf)
                        +
                        (SELECT MIN(Cost) FROM
                            (SELECT TOP 50 PERCENT Cost FROM #Temp WHERE Cost <> 0 ORDER BY Cost DESC) AS TopHalf)
                    )) / 2)     


SELECT * FROM #Temp
DROP TABLE #Temp

中位数计算不正确

Median worked out incorrectly

sql

sql-server

sql-server-2008-r2

median