SELECT count(*) FROM patient WHERE SSN NOT IN ( SELECT T1.patient FROM Prescribes AS T1 JOIN Medication AS T2 ON T1.Medication  =  T2.Code WHERE T2.name  =  'Procrastin-X' )
Find the number of patients who are not using the medication of Procrastin-X.
SELECT count ( * ) FROM patient WHERE SSN NOT IN ( SELECT T1.patient FROM Prescribes AS T1 JOIN Medication AS T2 ON T1.Medication = T2.Code WHERE T2.name = 'Procrastin-X ' )
select count ( * ) from patient where ssn not in ( select t1 . patient from prescribes as t1 join medication as t2 on t1 . medication = t2 . code where t2 . name = value )
Find the number of patients who are not using the medication of Procrastin-X .