*Execute one PROC only.  They do the same thing.;

proc datasets lib = ia;
   modify capinfo;
       ic create PKIDInfo = Primary Key (RouteId)
          message = 'You must supply a Route ID Number';
       ic create Class1 = check 
                         (where = (Cap1st < CapBusiness or  
                                   CapBusiness = .))
          Message = 'First Class Capacity must be less than 
                     Business Capacity';
	contents data = capinfo;
run;
quit;

*Execute one PROC only.  They do the same thing.;

proc sql;
   alter table ia.capinfo
       add constraint PKIDInfo Primary Key (RouteID) 
       add constraint Class1 check 
                                 (Cap1st < 
                                  CapBusiness or 
                                  CapBusiness = .);
   describe table constraints ia.capinfo;
quit;