SELECT customer_name ,  customer_phone FROM customers WHERE customer_id NOT IN (SELECT customer_id FROM mailshot_customers)
Show the name and phone of the customer without any mailshot.
SELECT customer_name , customer_phone FROM customers WHERE customer_id NOT IN ( SELECT customer_id FROM mailshot_customers )
select customer_name , customer_phone from customers where customer_id not in ( select customer_id from mailshot_customers )
Show the name and phone of the customer without any mailshot .