data work.profit work.errors;
   set ia.dnunder;
   set ia.sale2000(keep = RouteID FlightID Date Rev1st
                          RevBusiness RevEcon RevCargo)
                  key = FlightDate/unique;
   if _IORC_ = 0 then do;
       Profit = sum(Rev1st, RevBusiness, RevEcon,
                    RevCargo, - Expenses);
      output work.profit;
   end;
   else do;
      _error_ = 0;
	  output work.errors;
   end;
run;

proc print data = work.profit (firstobs = 895);
   title 'Combining Data Sets and Eliminating Non-matches';
run;


proc print data = work.errors;
   title 'Errors data';
run;