What episode was the first appearance of the character who appears 7 times in season 4?
CREATE TABLE "character_appearances" (
  "character" text,
  "played_by" text,
  "season_1" real,
  "season_2" real,
  "season_3" real,
  "season_4" real,
  "first_appearance" text
);
SELECT "first_appearance" FROM "character_appearances" WHERE "season_4"=7;