Here you go: data have; infile cards dsd; informat service_date mmddyy10.; format service_date mmddyy10.; input Patient_ID $ Drug_name $ Service_date; cards; 0001,Drug A,01/01/2007 0001,Drug B,01/10/2007 0001,Drug C,01/20/2007 0001,Drug A,02/01/2007 0001,Drug B,02/10/2007 0001,Drug C,02/20/2007 0001,Drug A,03/01/2007 0001,Drug B,03/10/2007 0001,Drug C,03/20/2007 ; proc sort data=have;by Patient_ID Drug_name; data want; set have; by Patient_ID drug_name; if first.Drug_name then drug_number +1; run;
... View more