What is the average bronze medal when gold is greater than 0, and there is less than 0 silver medals?
CREATE TABLE "medal_table" (
  "rank" real,
  "nation" text,
  "gold" real,
  "silver" real,
  "bronze" real,
  "total" real
);
SELECT AVG("bronze") FROM "medal_table" WHERE "gold">0 AND "silver"<0;