Subquery returned more than 1 value. This is not permitted when the subquery follows

Question

I have the following script which has stopped working due the error in the title. Could someone please provide some assistance?

SELECT DISTINCT TOP 100 PERCENT
         Locs.lCustomerGroupPK, Locs.lCustomerID, Locs.Customer_Group_Name, Locs.Customer_Name, Locs.Location_Name, TY.ThisYearsSales,
        (SELECT ThisYearsSales
           FROM dbo.Vw_Level_3_Sales_This_Year
          WHERE (lLocationID = Locs.lLocationID2 OR lLocationID = Locs.llocationid)
            AND (Current_Read_Date = TY.Current_Read_Date - 364) AND (ThisYearsSales <= 400)
         ) AS LastYearsSales, 
         TY.Current_Read_Date - 1 AS Current_Read_Date INTO #tmplocationlflsales
  FROM dbo.Vw_Level_3_Sales_This_Year AS TY 
        INNER JOIN dbo.vw_locations_Like_For_Like_Previous AS Locs 
                ON TY.lLocationID = Locs.llocationid OR TY.lLocationID = Locs.lLocationID2
 WHERE (TY.ThisYearsSales <= 400)
    AND (TY.Current_Read_Date = @RecordDate)
    AND TY.ThisYearsSales IS NOT NULL
    AND (SELECT ThisYearsSales
           FROM dbo.Vw_Level_3_Sales_This_Year
          WHERE (lLocationID = Locs.lLocationID2 OR lLocationID = Locs.llocationid) 
            AND (Current_Read_Date = TY.Current_Read_Date - 364) 
            AND (ThisYearsSales <= 400)
         ) IS NOT NULL 
 ORDER BY Locs.Customer_Group_Name, Locs.Customer_Name, Locs.Location_Name, Current_Read_Date

Answer 1

The problem would seem to be the subquery in the SELECT:

        SELECT ThisYearsSales
        FROM dbo.Vw_Level_3_Sales_This_Year
        WHERE (lLocationID = Locs.lLocationID2 OR 
                lLocationID = Locs.llocationid) 
            AND (Current_Read_Date = TY.Current_Read_Date - 364) 
            AND (ThisYearsSales <= 400)

This is returning too many rows. Perhaps you want to change it to:

        SELECT sum(ThisYearsSales)
        FROM dbo.Vw_Level_3_Sales_This_Year
        WHERE (lLocationID = Locs.lLocationID2 OR 
                lLocationID = Locs.llocationid) 
            AND (Current_Read_Date = TY.Current_Read_Date - 364) 
            AND (ThisYearsSales <= 400)

Since you use the same subquery twice, you should really put it in the FROM clause.

Answer 2

As far as I can see, you have this subquery in your script

SELECT ThisYearsSales
FROM dbo.Vw_Level_3_Sales_This_Year
WHERE (lLocationID = Locs.lLocationID2 OR lLocationID = Locs.llocationid) 
 AND (Current_Read_Date = TY.Current_Read_Date - 364) 
 AND (ThisYearsSales <= 400)

If this returns a single value (one column in one record), than it will be included in your result, however, if this returns more than one row, you'll get the error you're getting.

Take a look at the data in the Vw_Level_3_Sales_This_Year view to see if there are duplicates per lLocationID / Current_Read_Date, since those are the fields you are filtering by. Something along the lines of:

SELECT count(*), lLocationID, Current_Read_Date 
FROM dbo.Vw_Level_3_Sales_This_Year
GROUP BY lLocationID, Current_Read_Date 
HAVING count(*)>1

Any rows returned by this query should indicate where the problem is.