Which rd. took place at Hockenheimring?
CREATE TABLE "season_review" (
  "rd" real,
  "grand_prix" text,
  "date" text,
  "location" text,
  "pole_position" text,
  "fastest_lap" text,
  "winning_driver" text,
  "constructor" text,
  "report" text
);
SELECT MIN("rd") FROM "season_review" WHERE "location"='Hockenheimring';