What was the overall draft pick of the player who was a db and attended college in iowa?
CREATE TABLE "washington_redskins_draft_history" (
  "round" real,
  "pick" real,
  "overall" real,
  "name" text,
  "position" text,
  "college" text
);
SELECT "overall" FROM "washington_redskins_draft_history" WHERE "college"='iowa' AND "position"='db';