in 12/2105 was patient 51858 prescribed 5% dextrose?
select count(*)>0 from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 51858 ) and prescriptions.drug = '5% dextrose' and strftime('%y-%m',prescriptions.startdate) = '2105-12'