What is the lowest number of silvers for countries in rank 12 with more than 0 bronze?
CREATE TABLE "medals_table" (
  "rank" text,
  "nation" text,
  "gold" real,
  "silver" real,
  "bronze" real,
  "total" real
);
SELECT MIN("silver") FROM "medals_table" WHERE "rank"='12' AND "bronze">0;