Please give the full name of the customer that have rented the most films.
full name refers to first_name, last_name; customer who rented the most film refers to Max(count(rental_id))
SELECT T.first_name, T.last_name FROM ( SELECT T1.first_name, T1.last_name, COUNT(T2.rental_id) AS num FROM customer AS T1 INNER JOIN rental AS T2 ON T1.customer_id = T2.customer_id GROUP BY T1.first_name, T1.last_name ) AS T ORDER BY T.num DESC LIMIT 1