คนไข้คนไหนเข้าโรงพยาบาลฉุกเฉิน?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
which patients had emergency hospital admission?It is not neccessary to use all the tables.
 procedures:  subject_id [ text]  hadm_id [ text]  icd9_code [ text]  short_title [ text]  long_title [ text] 
SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic WHERE demographic.admission_type = "EMERGENCY"