Starting from the Have dataset from the previous answers, this gives the same result: proc sql;   create table want as     select a.*, case when a.Facility_type='Nursing Home' and b.facility_type='Hospital' and                           b.admit_date le a.disch_date then 1                      else 0                 end as flag     from have a     left join have b       on a.patient_id=b.patient_id       and b.admit_date gt a.admit_date   group by a.patient_id, a.admit_date   having b.admit_date=min(b.admit_date); quit; ... View more