SELECT name FROM appointment AS T1 JOIN patient AS T2 ON T1.patient  =  T2.ssn
List the names of patients who have made appointments.
SELECT name FROM appointment AS T1 JOIN patient AS T2 ON T1.patient = T2.ssn
select name from appointment as t1 join patient as t2 on t1 . patient = t2 . ssn
List the names of patients who have made appointments .