in total, count the number of times patient 29806 had been prescribed 5% dextrose in 07/last year.
select count(*) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 29806 ) and prescriptions.drug = '5% dextrose' and datetime(prescriptions.startdate,'start of year') = datetime(current_time,'start of year','-1 year') and strftime('%m',prescriptions.startdate) = '07'