How many films rented on 26th May, 2005 were returned on 30th May, 2005?
rented on 26th May 2005 refers to rental_date = '2005-05-26'; return on 30th May, 2005 refers to return_date = '2005-05-30'; number of rented film refers to Count (rental_id)
SELECT COUNT(DISTINCT rental_id) FROM rental WHERE date(rental_date) BETWEEN '2005-05-26' AND '2005-05-30'