Question

I am using SQL Server 2008

I have a table of sales orders structured like this

PartNo  Desc      OrderDate      OrderQty
60001   widget1   Apr-02-2012    3
60001   widget1   Apr-14-2012    5
60001   widget1   Jun-04-2012    3
60002   widget2   Jan-03-2012    1
60002   widget2   jan-17-2012    1
60002   widget2   aug-04-2012    30
60002   widget2   sep-02-2012    1
60003   widget3   oct-01-2012    4
60003   widget3   oct-04-2012    7
60003   widget3   oct-17-2012    3
60004   widget4   nov-04-2011    8
60004   widget4   nov-05-2011    8
60004   widget4   nov-05-2012    8
60004   widget4   nov-07-2012    7

I want to return a table that is the max of the total per month for each item. It would look like this

PartNo    Desc     MaxSoldPerMonth  Month  Year
60001     widget1  8                Apr    2012
60002     widget2  30               Aug    2012
60003     widget3  14               oct    2012
60004     widget4  16               nov    2011

the months are actually in number format(i.e. nov = 11, oct = 10, apr = 4, ect) i just made it this way to make it easy to read. Thanks

Answer 1

This should do it:

;WITH MonthlyOrders AS
(
    SELECT PartNo, [Desc], CONVERT(VARCHAR(6),OrderDate,112) YearMonth, SUM(OrderQty) OrderQty
    FROM YourTable
    GROUP BY PartNo, [Desc], CONVERT(VARCHAR(6),OrderDate,112)
),MaxOrders AS
(
    SELECT *, ROW_NUMBER() OVER(PARTITION BY PartNo, [Desc] ORDER BY OrderQty DESC) RN
    FROM MonthlyOrders
)
SELECT PartNo, [Desc], OrderQty MaxSoldPerMonth, YearMonth
FROM MaxOrders
WHERE RN = 1;