Which artist has the least albums?
select t2.name from album as t1 join artist as t2 on t1.artistid = t2.artistid group by t2.name order by count(*) asc limit 1
How about the most albums?
select t2.name from album as t1 join artist as t2 on t1.artistid = t2.artistid group by t2.name order by count(*) desc limit 1