was the senna prescribed to patient 26849 in 08/last year?
select count(*)>0 from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 26849 ) and prescriptions.drug = 'senna' and datetime(prescriptions.startdate,'start of year') = datetime(current_time,'start of year','-1 year') and strftime('%m',prescriptions.startdate) = '08'