Table schema:
CREATE TABLE customer (first_name VARCHAR, customer_id VARCHAR, rental_date INTEGER); CREATE TABLE rental (first_name VARCHAR, customer_id VARCHAR, rental_date INTEGER)

Question: What are the first names of customers who have not rented any films after '2005-08-23 02:06:01'?
SQL: SELECT first_name FROM customer WHERE NOT customer_id IN (SELECT customer_id FROM rental WHERE rental_date > '2005-08-23 02:06:01')