so_refs_extract.sql

SELECT
    q.id id,
    q.title title,
    q.creation_date creation_date,
    t.repo repo,
    t.branch branch,
    t.path path,
    t.ext ext,
    t.line_number line_number
  FROM
    [bigquery-public-data:stackoverflow.posts_questions] q
  JOIN (
    SELECT *
    FROM (
      SELECT
        a.parent_id AS question_id,
        b.repo AS repo,
        b.branch as branch,
        b.path as path,
        b.ext as ext,
        b.line_number as line_number
      FROM
        [bigquery-public-data:stackoverflow.posts_answers] a
      JOIN
        (select Integer(answer_id) answer_id, repo, branch, path, ext, line_number 
        from [Dataset1.so_ref_top_repos_top_langs] where answer_id is not null) b
      ON
        a.id = b.answer_id),
      (
      SELECT
        a.id AS question_id,
        b.repo AS repo,
        b.branch as branch,
        b.path as path,
        b.ext as ext,
        b.line_number as line_number       
      FROM
        [bigquery-public-data:stackoverflow.posts_questions] a
      JOIN
        (select Integer(question_id) question_id, repo, branch, path, ext, line_number 
        from [Dataset1.so_ref_top_repos_top_langs] where question_id is not null) b
      ON
        a.id = b.question_id) ) t
  ON
    t.question_id = q.id