Подзапросы в FROM, задача 3

--Найдите средние значения полей, в которых указаны минимальная и максимальная длительность отобранных фильмов. Отобразите только два этих поля. Назовите их avg_min_length и avg_max_length соответственно.

SELECT AVG(min_length) AS avg_min_length,
       AVG(max_length) AS avg_max_length
FROM
  (SELECT top.rating,
          MIN(top.LENGTH) AS min_length,
          MAX(top.LENGTH) AS max_length,
          AVG(top.LENGTH) AS avg_length,
          MIN(top.rental_rate) AS min_rental_rate,
          MAX(top.rental_rate) AS max_rental_rate,
          AVG(top.rental_rate) AS avg_rental_rate
   FROM
     (SELECT title,
             rental_rate,
             LENGTH,
             rating
      FROM movie
      WHERE rental_rate > 2
      ORDER BY LENGTH DESC
      LIMIT 40) AS top
   GROUP BY top.rating
   ORDER BY avg_length) AS sub;