What team were the bills playing where their first down was 23?
CREATE TABLE "schedule" (
  "game" real,
  "date" text,
  "opponent" text,
  "result" text,
  "bills_points" real,
  "opponents" real,
  "bills_first_downs" real,
  "record" text,
  "attendance" real
);
SELECT "opponent" FROM "schedule" WHERE "bills_first_downs"=23;