options ls=120 ps=60;

filename foo1 url "http://www.uvm.edu/~abh/stat295/datasets/milk.dat";

data milk;
     infile foo1 dlm=',';
	 input date:mmddyy8. day cow period treatment lbs_milk;
	 format date date9.;
run;

proc print data=milk;
title "Pounds of milk per cow per day";
run;

filename foo2 url "http://www.uvm.edu/~abh/stat295/datasets/calf.dat";

data calf;
     infile foo2 dlm=',';
	 input cow calfdate:mmddyy8. ;
	 format calfdate date9.;
run;

proc print data=calf;
title "Calfing date";
run;

proc sort data=milk;
     by cow;
run;

proc sort data=calf;
     by cow;
run;

data milk;
     merge milk calf;
	 by cow;
	 days_in_milk = date - calfdate;
run;

proc print data=milk;
title "Days in milk";
run;