CREATE TABLE "table1_16581695_4" (
  "no_in_series" text,
  "no_in_season" text,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_airdate" text,
  "production_code" text
);

Question: What is the series episode number of the episode with production code 303?
SQL: SELECT "no_in_series" FROM "table1_16581695_4" WHERE "production_code"='303';

Question: What is the production code for episode 15 in season 3?
SQL: SELECT "production_code" FROM "table1_16581695_4" WHERE "no_in_season"='15';

Question: Who directed episode 12 in season 3?
SQL: SELECT "directed_by" FROM "table1_16581695_4" WHERE "no_in_season"='12';