and what was the last time patient 30826 was prescribed medication using the po/ng route in their current hospital encounter?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 30826 and admissions.dischtime is null ) and prescriptions.route = 'po/ng' order by prescriptions.startdate desc limit 1