Hello!  Can you provide me with a list of the first names of all customers who rented films before '2005-08-23 02:06:01'?
SELECT first_name FROM customer WHERE customer_id IN  (  SELECT customer_id FROM rental WHERE rental_date  <  '2005-08-23 02:06:01'  ) 
list of first names = SELECT first_name; all customers who rented films before a specific date refers to WHERE rental_date < '2005-08-23 02:06:01';