Select SQL results grouped by weeks

Question

I want to select data from following table group by weeks

 Date       Product Name   Sale
+----------+--------------+-----+
 14-05-11     a             2
 14         


        

Answer 1

I think this should do it..

Select 
ProductName,
WeekNumber,
sum(sale)
from
(
    SELECT 
    ProductName,
    DATEDIFF(week, '2011-05-30', date) AS WeekNumber,
    sale
    FROM table
)
GROUP BY
ProductName,
WeekNumber