Show card types with at least 5 cards?
select card_type_code from customers_cards group by card_type_code having count ( * ) > = 5
yes
select card_id from customers_cards
What card type did customer number 14 use?
select card_type_code from customers_cards where customer_id = 14
How about customer number 6?
select card_type_code from customers_cards where customer_id = 6