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
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE Customers_cards (customer_id VARCHAR) Question: Show all customer ids and the number of cards owned by each customer. [/INST] SELECT customer_id, COUNT(*) FROM Customers_cards GROUP BY customer_id </s>