when did patient 21074 come for the last time until 2 years ago via the transfer from hosp/extram into the hospital?
select admissions.admittime from admissions where admissions.subject_id = 21074 and admissions.admission_location = 'transfer from hosp/extram' and datetime(admissions.admittime) <= datetime(current_time,'-2 year') order by admissions.admittime desc limit 1