What is the average population for an area less than 433.7km and a 23013 code?
CREATE TABLE "main_places" (
  "place" text,
  "code" real,
  "area_km_2" real,
  "population" real,
  "most_spoken_language" text
);
SELECT AVG("population") FROM "main_places" WHERE "area_km_2"<433.7 AND "code"=23013;