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

What are the names, ages, and countries of artists, sorted by the year they joined?
SELECT name, age, country FROM artist ORDER BY year_join
SELECT "name", "age", "country" FROM "artist" ORDER BY "year_join" NULLS FIRST