What is the theme and artist name for the exhibition 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 ) 
theme refers to exhibition.theme; artist name refers to artist.name; ticket price higher than the average refers to exhibition.ticket_price > AVG(exhibition.ticket_price);