what is the dose of vitamin d, that patient 8324 was last prescribed in 08/last year?
select prescriptions.dose_val_rx from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 8324 ) and prescriptions.drug = 'vitamin d' and datetime(prescriptions.startdate,'start of year') = datetime(current_time,'start of year','-1 year') and strftime('%m',prescriptions.startdate) = '08' order by prescriptions.startdate desc limit 1