Task: Text to Code
Input (English): Show all cities where at least one customer lives in but no performer lives in.
Output (English): 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