average_ratings_by_year_genre.sql

CREATE OR REPLACE TEMP TABLE AVERAGE_RATINGS_BY_YEAR_GENRE AS
  WITH T1 AS ( -- T1 -> Common Table Expression (CTE)
    SELECT r.rating, r.year, unnest(f.genres) AS genre
    FROM Films f JOIN Ratings r ON (r.film_id = f.film_id)
  )
  SELECT year, genre, avg(rating) AS average_rating
  FROM T1
  GROUP BY year, genre
  ORDER BY year DESC, genre