Show all customer ids and the number of cards owned by each customer.
CREATE TABLE Customers_cards (customer_id VARCHAR)
SELECT customer_id, COUNT(*) FROM Customers_cards GROUP BY customer_id
### Context: CREATE TABLE Customers_cards (customer_id VARCHAR) ### Question: Show all customer ids and the number of cards owned by each customer. ### Answer: SELECT customer_id, COUNT(*) FROM Customers_cards GROUP BY customer_id