[HR] Placements*

• Advanced Join > multiple joins on the same table and compare
  https://www.hackerrank.com/challenges/placements/problem?isFullScreen=true

select s.name
from students s
left join friends f
on s.id = f.id
left join packages p1
on f.id = p1.id
left join packages p2
on f.friend_id = p2.id
where p1.salary < p2.salary
order by p2.salary