Table: episode_info_3
Columns: no_in_series
no_in_season
title
directed_by
written_by
original_airdate
production_code

Question: What is the series episode number of the episode with production code 303?
SQL: SELECT "no_in_series" FROM episode_info_3 WHERE "production_code" = '303'

Question: What is the production code for episode 15 in season 3?
SQL: SELECT "production_code" FROM episode_info_3 WHERE "no_in_season" = '15'

Question: Who directed episode 12 in season 3?
SQL: SELECT "directed_by" FROM episode_info_3 WHERE "no_in_season" = '12'