Find the name of medication used on the patient who stays in room 111?
SELECT T4.name FROM stay AS T1 JOIN patient AS T2 ON T1.Patient  =  T2.SSN JOIN Prescribes AS T3 ON T3.Patient  =  T2.SSN JOIN Medication AS T4 ON T3.Medication  =  T4.Code WHERE room  =  111
name of medication used on the patient refers to T4.name; patient who stays in room refers to room = 111; relationships between tables: stay is joined with patient on Patient = SSN, Prescribes is joined with patient on Patient = SSN, Medication is joined with Prescribes on Medication = Code;