How many dates did the episode with a production code of 804 originally air on?
CREATE TABLE "table1_27988559_1" (
  "no_in_series" real,
  "no_in_season" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" real
);
SELECT COUNT("original_air_date") FROM "table1_27988559_1" WHERE "production_code"=804;