CREATE TABLE "season_4_2000" (
  "episode_num" text,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_airdate" text
);

Question: What was the original air date when ed horowitz wrote it?
SQL: SELECT "original_airdate" FROM "season_4_2000" WHERE "written_by"='ed horowitz';

Question: Name the episode number that aired on july 23, 2000
SQL: SELECT "episode_num" FROM "season_4_2000" WHERE "original_airdate"='july 23, 2000';