SELECT c.name AS category, avg(rental_rate)AS avg_rental_rate
FROM category c
left JOIN film_category ON c.category_id = film_category.category_id
left join film on film_category.film_id = film.film_id
--left JOIN inventory ON film_category.film_id = inventory.film_id
--left JOIN rental ON inventory.inventory_id = rental.inventory_id
--left JOIN payment ON rental.rental_id = payment.rental_id
GROUP BY 1
ORDER BY avg_rental_rate desc