What city has riverside ground as the venue, with a year prior to 1998?
CREATE TABLE "largest_margin_of_runs_victory" (
  "score" text,
  "opposition" text,
  "venue" text,
  "city" text,
  "year" real
);
SELECT "city" FROM "largest_margin_of_runs_victory" WHERE "venue"='riverside ground' AND "year"<1998;