CREATE TABLE ship (Ship_ID INT, Name TEXT, Type TEXT, Nationality TEXT, Tonnage INT)
CREATE TABLE mission (Mission_ID INT, Ship_ID INT, Code TEXT, Launched_Year INT, Location TEXT, Speed_knots INT, Fate TEXT)

Show different types of ships and the average tonnage of ships of each type Show bar chart, show in descending by the y-axis.
SELECT Type, AVG(Tonnage) FROM ship GROUP BY Type ORDER BY AVG(Tonnage) DESC
SELECT "Type", AVG("Tonnage") FROM "ship" GROUP BY "Type" ORDER BY AVG("Tonnage") DESC NULLS LAST