CREATE TABLE Clients (Customer_Name VARCHAR2, Client_ID VARCHAR2)
CREATE TABLE Bookings (Customer_ID VARCHAR2)

Show the names of all the clients with no booking.
SELECT Customer_Name FROM Clients EXCEPT SELECT T2.Customer_Name FROM Bookings AS T1 JOIN Clients AS T2 ON T1.Customer_ID = T2.Client_ID
SELECT "Customer_Name" FROM "Clients" EXCEPT SELECT "T2"."Customer_Name" FROM "Bookings" "T1" JOIN "Clients" "T2" ON "T1"."Customer_ID" = "T2"."Client_ID"