Count number of records returned by group by

Question

How do I count the number of records returned by a group by query,

For eg:

select count(*) 
from temptable
group by column_1, column_2, column_3, co         


        

Answer 1

How about using a COUNT OVER (PARTITION BY {column to group by}) partitioning function in SQL Server?

For example, if you want to group product sales by ItemID and you want a count of each distinct ItemID, simply use:

SELECT
{columns you want} ,
COUNT(ItemID) OVER (PARTITION BY ItemID) as BandedItemCount ,
{more columns you want}... ,
FROM {MyTable}

If you use this approach, you can leave the GROUP BY out of the picture -- assuming you want to return the entire list (as you might do report banding where you need to know the entire count of items you are going to band without having to display the entire set of data, i.e. Reporting Services).