มีผู้ป่วยกี่รายที่ไม่ได้ใช้ Procrastin-X เป็นยา?ไม่จำเป็นต้องใช้ทุกตาราง
How many patients are not using Procrastin-X as medication?It is not neccessary to use all the tables.
 stay:  stayid [ number]  patient [ number]  room [ number]  staystart [ time]  stayend [ time] 
SELECT COUNT(*) FROM patient WHERE NOT ssn IN (SELECT T1.patient FROM prescribes AS T1 JOIN medication AS T2 ON T1.medication = T2.code WHERE T2.name = 'Procrastin-X')