CREATE TABLE table_204_320 (id DECIMAL, "rank" DECIMAL, "nation" TEXT, "gold" DECIMAL, "silver" DECIMAL, "bronze" DECIMAL, "total" DECIMAL)

which country received the least bronze medals ?
SELECT "nation" FROM table_204_320 ORDER BY "bronze" LIMIT 1
SELECT "nation" FROM "table_204_320" ORDER BY "bronze" NULLS FIRST LIMIT 1