CREATE TABLE ship (ship_id NUMBER, name CLOB, type CLOB, nationality CLOB, tonnage NUMBER)
CREATE TABLE mission (mission_id NUMBER, ship_id NUMBER, code CLOB, launched_year NUMBER, location CLOB, speed_knots NUMBER, fate CLOB)

What is the most common type of ships?
SELECT type FROM ship GROUP BY type ORDER BY COUNT(*) DESC LIMIT 1
SELECT "type" FROM "ship" GROUP BY "type" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY