show info of all airlines.
select * from airlines
find the number of routes for each airline. Show their names.
select count(*), t1.name from airlines as t1 join routes as t2 on t1.alid = t2.alid group by t1.name
which airline has the most routes?
select t1.name from airlines as t1 join routes as t2 on t1.alid = t2.alid group by t1.name order by count(*) desc limit 1