Show all exhibitions.
select * from exhibition
What is the average ticket price?
select avg(ticket_price) from exhibition
Which exhibitions have a ticket price higher than the average?
select * from exhibition where ticket_price > (select avg(ticket_price) from exhibition)
What are the themes and artist names for the exhibitions with a ticket price higher than the average?
select t1.theme, t2.name from exhibition as t1 join artist as t2 on t1.artist_id = t2.artist_id where t1.ticket_price > (select avg(ticket_price) from exhibition)