CREATE TABLE exhibition_record (Exhibition_ID NUMBER, Date CLOB, Attendance NUMBER)
CREATE TABLE exhibition (Exhibition_ID NUMBER, Year NUMBER, Theme CLOB, Artist_ID NUMBER, Ticket_Price FLOAT)
CREATE TABLE artist (Artist_ID NUMBER, Name CLOB, Country CLOB, Year_Join NUMBER, Age NUMBER)

Stacked bar of year and the number of year colored by Theme
SELECT Year, COUNT(Year) FROM exhibition GROUP BY Theme
SELECT "Year", COUNT("Year") FROM "exhibition" GROUP BY "Theme"