คนไข้ที่นัดหมายชื่ออะไร ไม่จำเป็นต้องใช้ทุกตาราง
What are names of patients who made an appointment?It is not neccessary to use all the tables.
 trained_in:  physician [ number]  treatment [ number]  certificationdate [ time]  certificationexpires [ time] 
SELECT name FROM appointment AS T1 JOIN patient AS T2 ON T1.patient = T2.ssn