Context: CREATE TABLE payment (customer_id VARCHAR); CREATE TABLE customer (first_name VARCHAR, last_name VARCHAR, customer_id VARCHAR)
Question: Which customer, who has made at least one payment, has spent the least money? List his or her first name, last name, and the id.
Answer: SELECT T1.first_name, T1.last_name, T1.customer_id FROM customer AS T1 JOIN payment AS T2 ON T1.customer_id = T2.customer_id GROUP BY T1.customer_id ORDER BY SUM(amount) LIMIT 1