CREATE TABLE exhibition (exhibition_id NUMBER, year NUMBER, theme CLOB, artist_id NUMBER, ticket_price NUMBER)
CREATE TABLE exhibition_record (exhibition_id NUMBER, date CLOB, attendance NUMBER)
CREATE TABLE artist (artist_id NUMBER, name CLOB, country CLOB, year_join NUMBER, age NUMBER)

What are all distinct country for artists?
SELECT DISTINCT country FROM artist
SELECT DISTINCT "country" FROM "artist"