Group By Clause

Hi experts,

I am using group by clause in a select statement. Their is no problem in select statement. My need is to find how many groups are retrived form that select statement. eg, In a report program i am generating PO item list created for a day such that i am grouping PO items with reference to PO Number.At the same time i also need the number PO's created for a day. Methods like looping throught internal table,etc are possible but i want system field that will give no of groups from the select statement itself.

With Regards,

Rk