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 NUMBER, class CLOB, flag CLOB)

Which classes have more than two captains?
SELECT class FROM captain GROUP BY class HAVING COUNT(*) > 2
SELECT "class" FROM "captain" GROUP BY "class" HAVING COUNT(*) > 2