What is the rank of a country with more than 2 gold, less than 5 silver, and less than 31 total medals?
CREATE TABLE "performances_by_nation" (
  "rank" real,
  "gold" real,
  "silver" real,
  "bronze" real,
  "total" real
);
SELECT SUM("rank") FROM "performances_by_nation" WHERE "gold">2 AND "total"<31 AND "silver"<5;