캐글​ advanced_sql/01-joins-and-unions

first_query = """
              SELECT q.id AS q_id,
                  MIN(TIMESTAMP_DIFF(a.creation_date, q.creation_date, SECOND)) as time_to_answer
              FROM `bigquery-public-data.stackoverflow.posts_questions` AS q
                  INNER JOIN `bigquery-public-data.stackoverflow.posts_answers` AS a
              ON q.id = a.parent_id
              WHERE q.creation_date >= '2018-01-01' and q.creation_date < '2018-02-01'
              GROUP BY q_id
              ORDER BY time
              """
​
correct_query = """
                SELECT q.id AS q_id,
                    MIN(TIMESTAMP_DIFF(a.creation_date, q.creation_date, SECOND)) as time_to_answer
                FROM `bigquery-public-data.stackoverflow.posts_questions` AS q
                    LEFT JOIN `bigquery-public-data.stackoverflow.posts_answers` AS a
                ON q.id = a.parent_id
                WHERE q.creation_date >= '2018-01-01' and q.creation_date < '2018-02-01'
                GROUP BY q_id
                ORDER BY time_to_answer
                """​
​
q_and_a_query = """
                SELECT q.owner_user_id AS owner_user_id,
                    MIN(q.creation_date) AS q_creation_date,
                    MIN(a.creation_date) AS a_creation_date
                FROM `bigquery-public-data.stackoverflow.posts_questions` AS q
                    FULL JOIN `bigquery-public-data.stackoverflow.posts_answers` AS a
                ON q.owner_user_id = a.owner_user_id 
                WHERE q.creation_date >= '2019-01-01' AND q.creation_date < '2019-02-01' 
                    AND a.creation_date >= '2019-01-01' AND a.creation_date < '2019-02-01'
                GROUP BY owner_user_id
                """​
​
three_tables_query = """
                     SELECT u.id AS id,
                         MIN(q.creation_date) AS q_creation_date,
                         MIN(a.creation_date) AS a_creation_date
                     FROM `bigquery-public-data.stackoverflow.users` AS u
                         LEFT JOIN `bigquery-public-data.stackoverflow.posts_questions` AS q
                             ON u.id = q.owner_user_id
                         LEFT JOIN `bigquery-public-data.stackoverflow.posts_answers` AS a
                             ON u.id = a.owner_user_id 
                     WHERE u.creation_date >= '2019-01-01' AND u.creation_date < '2019-02-01'
                     GROUP BY id
                     """​
​
all_users_query = """
                  SELECT q.owner_user_id AS owner_user_id
                  FROM `bigquery-public-data.stackoverflow.posts_questions` AS q
                  WHERE EXTRACT(DATE FROM q.creation_date) = '2019-01-01'
                  UNION DISTINCT
                  SELECT a.owner_user_id AS owner_user_id
                  FROM `bigquery-public-data.stackoverflow.posts_answers` AS a
                  WHERE EXTRACT(DATE FROM a.creation_date) = '2019-01-01'
                  """​
​