What are the different card types, and how many cards are there of each?
SELECT card_type_code ,  count(*) FROM Customers_cards GROUP BY card_type_code
SELECT card_type_code ,  count(*) FROM Customers_cards GROUP BY card_type_code
[{'card_type_code': 'Credit', 'count(*)': 7}, {'card_type_code': 'Debit', 'count(*)': 8}]