Which songs are in mp3 format?
select t2.song_name from files as t1 join song as t2 on t1.f_id = t2.f_id where t1.formats = "mp3"
Of the which have resolution below 1000?
select t2.song_name from files as t1 join song as t2 on t1.f_id = t2.f_id where t1.formats = "mp3" intersect select song_name from song where resolution < 1000
What is their actual resolution?
select song_name, resolution from song where song_name in ( select t2.song_name from files as t1 join song as t2 on t1.f_id = t2.f_id where t1.formats = "mp3" intersect select song_name from song where resolution < 1000 )