how many times was the metoclopramide prescribed in this month for patient 42829?
select count(*) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 42829 ) and prescriptions.drug = 'metoclopramide' and datetime(prescriptions.startdate,'start of month') = datetime(current_time,'start of month','-0 month')