What is the episode # of the episode that aired on April 5, 1998?
CREATE TABLE "season_2_1998" (
  "episode_num" text,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_airdate" text
);
SELECT "episode_num" FROM "season_2_1998" WHERE "original_airdate"='april 5, 1998';