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

What is the number of countries in the artist table?, and I want to rank how many country in descending order.
SELECT Country, COUNT(Country) FROM artist GROUP BY Country ORDER BY COUNT(Country) DESC
SELECT "Country", COUNT("Country") FROM "artist" GROUP BY "Country" ORDER BY COUNT("Country") DESC NULLS LAST