Often in a program, you need to know whether variables are equal to each other, or whether they are greater than or less than each other. To compare two numeric variables, you can write an IF-THEN/ELSE statement using logical operators.

In this example, the total cost of each tour in the POPULARTOURS data set is compared to 2000 using the greater-than logical operator (gt). If the total cost of the tour is greater than 2000, the tour is excluded from the data set. The resulting data set TOURSUNDER2K contains tours that are $2000 or less.

data toursunder2K;
   set mylib.populartours;
   TotalCost = AirCost + LandCost;
 if TotalCost gt 2000 then delete;
run;
proc print data=toursunder2K;
   var Country Nights AirCost Landcost TotalCost Vendor;
   title 'Tours $2000 or Less';
run;

The TotalCost value for Greece is a missing value because any calculation that includes a missing value results in a missing value. In a comparison, missing numeric values are lower than any other numeric value.

If you need to compare a variable to more than one value, you can include multiple comparisons in a condition. To eliminate tours with missing values, a second comparison is added:

data toursunder2K2;
   set mylib.populartours;
   TotalCost = AirCost + LandCost;
   if TotalCost gt 2000 or Totalcost = . then delete;
run;

proc print data=toursunder2K2;
   var Country Nights TotalCost Vendor;
   title 'Tours $2000 or Less';
run;

Notice that Greece is no longer included in the tours for under $2000.