AMDP Select with TOP 3 entries based on certain fields

Dear colleagues,

I’m creating an AMDP to getting the top 3 vendors based on certain fields.
I have a table result with all the entries and now I have to build the second SELECT to get the top 3 vendors, grouped by vendor and sumerized and sorted by DMBTR
I’ll apreciate your help

Kind Regards
Mariano