ผู้ป่วยมีรหัสยา metl25 จำนวนเท่าใด ไม่จำเป็นต้องใช้ทุกตาราง
what is the number of patients whose drug code is metl25?It is not neccessary to use all the tables.
 diagnoses:  subject_id [ text]  hadm_id [ text]  icd9_code [ text]  short_title [ text]  long_title [ text] 
SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id WHERE prescriptions.formulary_drug_cd = "METL25"