SELECT name FROM patient EXCEPT SELECT T1.name FROM patient AS T1 JOIN Prescribes AS T2 ON T2.Patient  =  T1.SSN JOIN Medication AS T3 ON T2.Medication  =  T3.Code WHERE T3.name  =  'Procrastin-X'
What are the names of patients who are not taking the medication of Procrastin-X.
SELECT name FROM patient EXCEPT SELECT T1.name FROM patient AS T1 JOIN Prescribes AS T2 ON T2.Patient = T1.SSN JOIN Medication AS T3 ON T2.Medication = T3.Code WHERE T3.name = 'Procrastin-X '
select name from patient except select t1 . name from patient as t1 join prescribes as t2 on t2 . patient = t1 . ssn join medication as t3 on t2 . medication = t3 . code where t3 . name = value
What are the names of patients who are not taking the medication of Procrastin-X .