จำนวนผู้ป่วยในวอร์ด 14?ไม่จำเป็นต้องใช้ทุกโต๊ะ
the number of patients in ward 14?It is not neccessary to use all the tables.
 prescriptions:  row_id [ number]  subject_id [ number]  hadm_id [ number]  startdate [ time]  enddate [ time]  drug [ text]  dose_val_rx [ text]  dose_unit_rx [ text]  route [ text] 
SELECT COUNT(DISTINCT admissions.subject_id) FROM admissions WHERE admissions.hadm_id IN (SELECT transfers.hadm_id FROM transfers WHERE transfers.wardid = 14)