Phân tích độ dài bản nhạc

-- Create a CTE named track_lengths
___ ___ ___ (
	SELECT
        genre.name,
        track.genre_id,
        track.milliseconds / 1000 AS num_seconds
    FROM store.track
    JOIN store.genre ON track.genre_id = genre.genre_id
)

SELECT
    track_lengths.name,
    -- Find the average length of each track in seconds
    ___(___.___) AS avg_track_length
FROM ___
GROUP BY track_lengths.name
-- Sort the results by average track_length
___;