แสดงเมืองทั้งหมดที่มีลูกค้าอย่างน้อยหนึ่งรายอาศัยอยู่ แต่ไม่มีนักแสดงอาศัยอยู่ ไม่จำเป็นต้องใช้ตารางทั้งหมด
Show all cities where at least one customer lives in but no performer lives in.It is not neccessary to use all the tables.
 customers:  customer_id [ text]  address_id [ number]  customer_name [ text]  customer_phone [ text]  customer_email_address [ text]  other_details [ text] 
SELECT T1.city_town FROM addresses AS T1 JOIN customers AS T2 ON T1.address_id = T2.address_id EXCEPT SELECT T1.city_town FROM addresses AS T1 JOIN performers AS T2 ON T1.address_id = T2.address_id