List all the durations of the songs.
select duration from files
How many are there if the duration is only 3 mins to 4 mins?
select count(*) from files where duration like "3:%"
What about the ones which have the format to be mp4?
select count(*) from files where formats = "mp4"
Show the ids that the song is in mp4 and resolution is lower than 1000.
select f_id from files where formats = "mp4" intersect select f_id from song where resolution < 1000