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

Show the average of artists' age by country, and I want to order by the X-axis in asc.
SELECT Country, AVG(Age) FROM artist GROUP BY Country ORDER BY Country
SELECT "Country", AVG("Age") FROM "artist" GROUP BY "Country" ORDER BY "Country" NULLS FIRST