CREATE TABLE Flight (aid VARCHAR2)
CREATE TABLE Aircraft (name VARCHAR2, aid VARCHAR2)

Show names for all aircraft with at least two flights.
SELECT T2.name FROM Flight AS T1 JOIN Aircraft AS T2 ON T1.aid = T2.aid GROUP BY T1.aid HAVING COUNT(*) >= 2
SELECT "T2"."name" FROM "Flight" "T1" JOIN "Aircraft" "T2" ON "T1"."aid" = "T2"."aid" GROUP BY "T1"."aid" HAVING COUNT(*) >= 2