มีใบสั่งยา promethazine hcl กี่ใบ?ไม่จำเป็นต้องใช้ตารางทั้งหมด
how many promethazine hcl prescriptions have been prescribed?It is not neccessary to use all the tables.
 chartevents:  row_id [ number]  subject_id [ number]  hadm_id [ number]  icustay_id [ number]  itemid [ number]  charttime [ time]  valuenum [ number]  valueuom [ text] 
SELECT COUNT(*) FROM prescriptions WHERE prescriptions.drug = 'promethazine hcl'