CREATE TABLE captain (Captain_ID NUMBER, Name CLOB, Ship_ID NUMBER, age CLOB, Class CLOB, Rank CLOB)
CREATE TABLE Ship (Ship_ID NUMBER, Name CLOB, Type CLOB, Built_Year FLOAT, Class CLOB, Flag CLOB)

Return the average age of captains in each class.
SELECT Class, AVG(age) FROM captain GROUP BY Class
SELECT "Class", AVG("age") FROM "captain" GROUP BY "Class"