CREATE TABLE Financial_transactions (card_id VARCHAR(255)); CREATE TABLE Customers_cards (card_type_code VARCHAR(255), card_id VARCHAR(255))
Show the card type codes and the number of transactions.
    
SQL: SELECT T2.card_type_code, COUNT(*) FROM Financial_transactions AS T1 JOIN Customers_cards AS T2 ON T1.card_id = T2.card_id GROUP BY T2.card_type_code