Database: customers_card_transactions
Question: Show the customer ids and firstname without a credit card.
SQL:
SELECT customer_id ,  customer_first_name FROM Customers EXCEPT SELECT T1.customer_id ,  T2.customer_first_name FROM Customers_cards AS T1 JOIN Customers AS T2 ON T1.customer_id  =  T2.customer_id WHERE card_type_code  =  "Credit"