What was the playoff result where the league did not qualify in the Open Cup in 1998?
CREATE TABLE "year_by_year" (
  "year" real,
  "division" real,
  "league" text,
  "regular_season" text,
  "playoffs" text,
  "open_cup" text
);
SELECT "playoffs" FROM "year_by_year" WHERE "open_cup"='Did not qualify' AND "year"=1998;