What is the name and country for the artist with most number of exhibitions?
create table exhibition (artist_id varchar, PRIMARY KEY (artist_id)); create table artist (name varchar, country varchar, artist_id varchar, PRIMARY KEY (name))
select t2.name, t2.country from exhibition as t1 join artist as t2 on t1.artist_id = t2.artist_id group by t1.artist_id order by count(*) desc limit 1