On what date was the opponent Ayr United, the result 1–0, and the attendance more than 668?
CREATE TABLE "irn_bru_second_division" (
  "date" text,
  "opponent" text,
  "venue" text,
  "result" text,
  "attendance" real
);
SELECT "date" FROM "irn_bru_second_division" WHERE "result"='1–0' AND "attendance">668 AND "opponent"='ayr united';