มีผู้ป่วยที่อายุต่ำกว่า 77 ปีจำนวนกี่คนที่เข้ารับการผ่าตัดระบบทางเดินอาหารแบบ percu endosc gastrostomy ชื่อสั้น?ไม่จำเป็นต้องใช้ตารางทั้งหมด
how many patients below 77 years of age have undergone the procedure with short title percu endosc gastrostomy?It is not neccessary to use all the tables.
 demographic:  subject_id [ text]  hadm_id [ text]  name [ text]  marital_status [ text]  age [ text]  dob [ text]  gender [ text]  language [ text]  religion [ text]  admission_type [ text]  days_stay [ text]  insurance [ text]  ethnicity [ text]  expire_flag [ text]  admission_location [ text]  discharge_location [ text]  diagnosis [ text]  dod [ text]  dob_year [ text]  dod_year [ text]  admittime [ text]  dischtime [ text]  admityear [ text] 
SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN procedures ON demographic.hadm_id = procedures.hadm_id WHERE demographic.age < "77" AND procedures.short_title = "Percu endosc gastrostomy"