Question

I have to following query in SQL Server:

SELECT EmployeeID, 
       TotalQuantity AS TotalQty, 
       TotalSales, 
       MAX(CASE WHEN MonthNumber = MAX(MonthNumber)
           THEN TotalSales END) as RecentMonthSale
FROM vwSales 
GROUP BY EmployeeID, TotalQuantity , TotalSales

Bu it gives me the error:

Cannot perform an aggregate function on an expression
containing an aggregate or a subquery.

Input View is as follows:

EmployeeID    TotaSales MonthNumber
  1             4000      1
  1             6000      2
  2             8500      1
  2             6081      2 

Desired output:

EmployeeID    TotalSale     RecentMonthSale
  1            10000            6000
  2            14581            6081
  3            11458            1012 

I want following column in my output EmployeeID, TotalQuantity TotalSale RecentMonthSale My View has the following column EmployeeID TotalSale,TotalQuantity, MonthNumber.

Answer 1

This query will show the output that you need, and will scan the table only one time.

select EmployeeID, sum(TotalSales), sum(case when MaxMonth = 1 then TotalSales else 0 end) RecentMonthSales
from 
(
    select *, rank() over(order by MonthNumber desc) MaxMonth
    from
    (
        select EmployeeID, MonthNumber, sum(TotalSales) TotalSales
        from vwSales
        group by EmployeeID, MonthNumber
    ) tt
) tt
group by EmployeeID