Question

I’d like to rewrite the following select statement without the sub selects; while it works at the moment as it is it only works if there’s data, when one of the sub selects doesn’t return data I get an error

Each GROUP BY expression must contain at least one column that is not an outer reference.

This is the select:

SELECT  COUNT(DISTINCT ( PROMSID )) AS Volume ,
            ( SELECT    CAST(CAST(COUNT(DISTINCT ( PROMSID )) AS DECIMAL(8, 2))
                        / ( SELECT  COUNT(DISTINCT RES.Branch)
                            FROM    tblPROMsExportSummary AS PES
                                    INNER JOIN TVF_GetRelevantScorecards(@ProcedureID, 82, @StartDate, @EndDate) AS RES ON RES.PROMSID = PES.PROMSID
                                    INNER JOIN tblUploadedScorecards AS UPL ON PES.PROMSID = UPL.PEMSID
                            WHERE   RES.[Month] = TVF.MonthValue
                            GROUP BY TVF.MonthValue
                          ) AS DECIMAL(8, 2)) AS PCTAverage
              FROM      #RelevantSummaryPCT AS PCT
              WHERE     PCT.[Month] = TVF.[MonthValue]
              GROUP BY  TVF.[MonthValue]
            ) AS PCTAverage ,
            TVF.ShortMonth AS [Month]
    FROM    #RelevantSummary AS RS
            RIGHT OUTER JOIN TVF_Months(@StartDate, @EndDate) AS TVF ON TVF.MonthValue = RS.[Month]
    GROUP BY TVF.[MonthName] ,
            TVF.[MonthValue] ,
            TVF.ShortMonth ,
            TVF.DisplayOrder
    ORDER BY TVF.DisplayOrder

What I am looking to achieve is a a single set of data from 2 temp tables which store results for different levels of reporting. The Volume column is the volume of results for ‘my group’ and the PCTAverage is the volume of results across all groups. The selects for those 2 temp tables:

SELECT  DISTINCT
            PES.FKProcedureID ,
            PES.PROMSID ,
            UPL.PKID AS UploadID ,
            MONTH(UPL.ShopDate) AS [Month]
    INTO    #RelevantSummary
    FROM    tblPROMsExportSummary AS PES
            INNER JOIN TVF_GetRelevantScorecards(@ProcedureID, @AreaID, @StartDate, @EndDate) AS RES ON RES.PROMSID = PES.PROMSID
            INNER JOIN tblUploadedScorecards AS UPL ON PES.PROMSID = UPL.PEMSID

-- also get them for all PCTs, @AreaID hardcoded to 82
    SELECT  DISTINCT
            PES.FKProcedureID ,
            PES.PROMSID ,
            UPL.PKID AS UploadID ,
            MONTH(UPL.ShopDate) AS [Month]
    INTO    #RelevantSummaryPCT
    FROM    tblPROMsExportSummary AS PES
            INNER JOIN TVF_GetRelevantScorecards(@ProcedureID, 82, @StartDate, @EndDate) AS RES ON RES.PROMSID = PES.PROMSID
            INNER JOIN tblUploadedScorecards AS UPL ON PES.PROMSID = UPL.PEMSID

Answer 1

Using derived tables is what I was after, in the example above it can be achieved like this:

SELECT * FROM (
SELECT  DISTINCT
        PES.FKProcedureID ,
        PES.PROMSID ,
        UPL.PKID AS UploadID ,
        MONTH(UPL.ShopDate) AS [Month]
INTO    #RelevantSummary
FROM    tblPROMsExportSummary AS PES
        INNER JOIN TVF_GetRelevantScorecards(@ProcedureID, @AreaID, @StartDate, @EndDate) AS RES ON RES.PROMSID = PES.PROMSID
        INNER JOIN tblUploadedScorecards AS UPL ON PES.PROMSID = UPL.PEMSID ) AS T1 
INNER JOIN (

SELECT  DISTINCT
        PES.FKProcedureID ,
        PES.PROMSID ,
        UPL.PKID AS UploadID ,
        MONTH(UPL.ShopDate) AS [Month]
INTO    #RelevantSummaryPCT
FROM    tblPROMsExportSummary AS PES
        INNER JOIN TVF_GetRelevantScorecards(@ProcedureID, 82, @StartDate, @EndDate) AS RES ON RES.PROMSID = PES.PROMSID
        INNER JOIN tblUploadedScorecards AS UPL ON PES.PROMSID = UPL.PEMSID ) AS T2
ON T1.PROMSID = T2.PROMSID

To quote directly from the 4guys post

What we are doing is first getting the result set from our derived table (the SELECT statement in the FROM clause). Once we have that resultset, it is as though it was a table in itself. We then perform the SELECT on the derived table, returning our results! You can find another example of using derived tables here on 4GuysFromRolla.com in the article Obtaining Ranked Values from a Table page.

Though my final select looks more like this:

SELECT  ISNULL(Volume, 0) AS Volume ,
            ISNULL(PCTAverage, 0) AS PCTAverage ,
            ShortMonth AS [Month] ,
            DisplayOrder
    FROM    ( SELECT    COUNT(DISTINCT ( PROMSID )) AS Volume ,
                        RS.YearMonth
              FROM      @RelevantSummary AS RS
              GROUP BY  YearMonth ) AS RS
            INNER JOIN ( SELECT CAST(CAST(COUNT(PROMSID) AS DECIMAL(8, 3))
                                / ( SELECT  ISNULL(COUNT(DISTINCT RES.Branch), 1)
                                    FROM    tblPROMsExportSummary AS PES
                                            INNER JOIN TVF_GetRelevantScorecards(@ProcedureID, @RootReportLevelID, @ReportLevelID, @StartDate,
                                                                                 @EndDate) AS RES ON RES.PROMSID = PES.PROMSID
                                            INNER JOIN tblUploadedScorecards AS UPL ON PES.PROMSID = UPL.PEMSID
                                    WHERE   RES.YearMonth = PCT.YearMonth
                                    GROUP BY RES.YearMonth ) AS DECIMAL(8, 3)) AS PCTAverage ,
                                YearMonth
                         FROM   @RelevantSummaryPCT AS PCT
                         GROUP BY YearMonth ) AS PCT ON RS.YearMonth = PCT.YearMonth
            RIGHT OUTER JOIN ( SELECT   *
                               FROM     dbo.TVF_Months(@StartDate, @EndDate) ) AS TVF ON TVF.DisplayOrder = RS.YearMonth