Pull Purchase group for Purchase requisation??

Hi Experts,

In purchasing process, I need to pull the value for Purchasing group-EKGRP and then I need to check its existence!. (t024??)

I hv the values for Purchase requisation #, material, order type, plant.

So, pls. let me know,

1) How to get Pur.group, and

2) checking its existemnce?

thanq