MySQL GROUP BY virker ikke, når den migreres til SQL Server 2012

SQL Server fungerer som forventet. Du skal inkludere alle elementer i din SELECT liste i enten en GROUP BY eller i en samlet funktion:

SELECT *,(XS+S+M+L+XL+XXL+[1Size]+Custom) as Total 
FROM StockData  
-- GROUP BY ID,StyleNr,Customer,Color, XS,S,M,L,XL,XXL,[1Size],Custom
ORDER BY StyleNr,Customer,Color

Eller du kan muligvis bruge:

SELECT StyleNr,Customer,Color, SUM(XS+S+M+L+XL+XXL+[1Size]+Custom) as Total 
FROM StockData  
GROUP BY StyleNr,Customer,Color
ORDER BY StyleNr,Customer,Color;