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

Show theme and year for all exhibitions with ticket prices lower than 15.
SELECT theme, year FROM exhibition WHERE ticket_price < 15
SELECT "theme", "year" FROM "exhibition" WHERE "ticket_price" < 15