SELECT sum(milliseconds) FROM tracks;
SELECT albumid, avg(milliseconds) FROM tracks GROUP BY albumid;
SELECT tracks.albumid, title, SUM(milliseconds) FROM tracks INNER JOIN albums ON albums.albumid = tracks.albumid GROUP BY tracks.albumid;
SELECT tracks.albumid, title, SUM(milliseconds) FROM tracks INNER JOIN albums ON albums.AlbumId = tracks.albumid GROUP BY tracks.albumid HAVING SUM(milliseconds) > 1000000;
SELECT * FROM albums;
SELECT * FROM artists;
SELECT * FROM customers;
SELECT * FROM employees;
SELECT * FROM genres;
SELECT * FROM invoice_items;
SELECT * FROM invoices;
SELECT * FROM media_types;
SELECT * FROM playlist_track;
SELECT * FROM playlists;
SELECT * FROM tracks;