CREATE TABLE "series_3_spearhead_in_hong_kong" (
  "episode_num" text,
  "original_air_date_uk" text,
  "episode_title" text,
  "director" text,
  "writer" text,
  "cast" text
);

Question: What is the original air date of the episode "Another Happy Day"?
SQL: SELECT "original_air_date_uk" FROM "series_3_spearhead_in_hong_kong" WHERE "episode_title"='Another Happy Day';

Question: What is the title of the episode that aired on 13 august 1981?
SQL: SELECT "episode_title" FROM "series_3_spearhead_in_hong_kong" WHERE "original_air_date_uk"='13 August 1981';

Question: What is the original air date of episode 3-02?
SQL: SELECT "original_air_date_uk" FROM "series_3_spearhead_in_hong_kong" WHERE "episode_num"='3-02';

Question: Who are the cast members of episode 3-04?
SQL: SELECT "cast" FROM "series_3_spearhead_in_hong_kong" WHERE "episode_num"='3-04';