when was the first time in their last hospital visit patient 47295 was prescribed a drug via the oral route?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 47295 and admissions.dischtime is not null order by admissions.admittime desc limit 1 ) and prescriptions.route = 'oral' order by prescriptions.startdate asc limit 1