CREATE TABLE payment (customer_id VARCHAR)
CREATE TABLE customer (first_name VARCHAR, last_name VARCHAR, customer_id VARCHAR)

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.
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
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") NULLS FIRST LIMIT 1