/*  C06S5D01.sas */

data comparison199901(keep = Month BudgetFirst BudgetBusiness
                                                BudgetEconomy BudgetCargo
                                                SalesFirst SalesBusiness SalesEconomy
                                                SalesCargo);
    if _n_ = 1 then do until (eofb);
      set ia.Budget199901 end = eofb;
      link GetMon;
      BudgetFirst + BudgetRevenueFirstClass;
      BudgetBusiness + BudgetRevenueBusiness;
      BudgetEconomy + BudgetRevenueEconomy;
      BudgetCargo + BudgetRevenueCargo;
    end;
    set ia.Sales199901 end = eofs;
    link GetMon;
    SalesFirst + SalesRevenueFirstClass;
    SalesBusiness + SalesRevenueBusiness;
    SalesEconomy + SalesRevenueEconomy;
    SalesCargo + SalesRevenueCargo;
    if eofs;
return;

GetMon:
  Month = substr(SalesMonth, 1, 3);
return;

run;