What is the sum of Pick #, when Position is Guard, and when Round is greater than 2?
CREATE TABLE "nfl_draft" (
  "round" real,
  "pick_num" real,
  "player" text,
  "position" text,
  "college" text
);
SELECT SUM("pick_num") FROM "nfl_draft" WHERE "position"='guard' AND "round">2;