CREATE TABLE rental (first_name VARCHAR, customer_id VARCHAR, rental_date INT)
CREATE TABLE customer (first_name VARCHAR, customer_id VARCHAR, rental_date INT)

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