Naming the evaluated case statement field with concatenating input variable value

Question

Hi,
I am trying to add the input variable value to case statement evaluated field like below query:
declare @Year varchar(4)
select ProductCode,datepart(mm,Date) MonthValue,
  case when datepart(mm,Date) = 1 then sum(Price) else 0 END AS Jan+@Year,
  case when datepart(mm,Date) = 2 then sum(Price) else 0 END AS Feb+@Year,
  case when datepart(mm,Date) = 3 then sum(Price) else 0 END AS Mar+@Year,
  case when datepart(mm,Date) = 4 then sum(Price) else 0 END AS Apr+@Year,
  case when datepart(mm,Date) = 5 then sum(Price) else 0 END AS May+@Year,
  case when datepart(mm,Date) = 6 then sum(Price) else 0 END AS Jun+@Year,
  case when datepart(mm,Date) = 7 then sum(Price) else 0 END AS Jul+@Year,
  case when datepart(mm,Date) = 8 then sum(Price) else 0 END AS Aug+@Year,
  case when datepart(mm,Date) = 9 then sum(Price) else 0 END AS Sep+@Year,
  case when datepart(mm,Date) = 10 then sum(Price) else 0 END AS Oct+@Year,
  case when datepart(mm,Date) = 11 then sum(Price) else 0 END AS Nov+@Year,
  case when datepart(mm,Date) = 12 then sum(Price) else 0 END AS Dec+@Year
from Sales_Imports where datepart(yyyy,Date) = @Year
group by  ProductCode, datepart(mm,Date)
Please help me any other way as this is not working...
Thanks,
Srini

Answer 1

create table Sales_Imports (ProductCode int, Price int, [date] date)
insert into Sales_Imports values
(1,10,'1/1/2014'),(1,109,'2/1/2014'),(1,10,'1/1/2014'),(1,109,'12/1/2014'),
(2,10,'1/1/2014'),(2,109,'2/1/2014'),(2,10,'10/1/2014'),(2,109,'12/1/2014')
declare @Year varchar(4)='2014'
DECLARE @MaxCount INT, @SQL NVARCHAR(max) ,@i INT;
Set @MaxCount = 12 
SET @i = 0;
SET @SQL = '';
WHILE @i < @MaxCount
BEGIN
    SET @i = @i + 1;
    SELECT @SQL = @Sql + ', SUM(CASE WHEN datepart(mm,[Date]) = ' + cast(@i AS NVARCHAR(10)) + ' THEN  Price Else 0 END) AS ' +Left(DateName(month,Dateadd(month,@i-1,0)) ,3)+@Year
END
SET @SQL = N' SELECT  ProductCode, datepart(mm,Date) MonthValue ' + @SQL 
+ N' FROM  Sales_Imports
 where datepart(yyyy,Date) ='+ @Year + N'group by  ProductCode, datepart(mm,Date)
 Order by ProductCode, datepart(mm,Date)';
--PRINT @SQL;
execute (@SQL);
--Or your original one
declare @Year varchar(4)
Set @Year ='2014'
declare @SQL  Nvarchar(4000)
SET @SQL=
N' select ProductCode,datepart(mm,Date) MonthValue,
  case when datepart(mm,Date) = 1 then sum(Price) else 0 END AS [jan' +@year+'],
  case when datepart(mm,Date) = 2 then sum(Price) else 0 END AS [feb' +@year+'],
  case when datepart(mm,Date) = 3 then sum(Price) else 0 END AS [Mar'+@year+'],
  case when datepart(mm,Date) = 4 then sum(Price) else 0 END AS [Apr'+@year+'],
  case when datepart(mm,Date) = 5 then sum(Price) else 0 END AS [May'+@year+'],
  case when datepart(mm,Date) = 6 then sum(Price) else 0 END AS [june'+@year+'],
  case when datepart(mm,Date) = 7 then sum(Price) else 0 END AS [july'+@year+'],
  case when datepart(mm,Date) = 8 then sum(Price) else 0 END AS [Aug'+@year+'],
  case when datepart(mm,Date) = 9 then sum(Price) else 0 END AS [Sep'+@year+'],
  case when datepart(mm,Date) = 10 then sum(Price) else 0 END AS [Oct'+@year+'],
  case when datepart(mm,Date) = 11 then sum(Price) else 0 END AS [Nov'+@year+'],
  case when datepart(mm,Date) = 12 then sum(Price) else 0 END AS [Dec'+@year+']
from Sales_Imports where datepart(yyyy,Date) = ' + @Year +N' group by  ProductCode, datepart(mm,Date)'
--print @Query
Execute (@SQL)
drop table Sales_Imports