text: SELECT
      hacker_id,
      name,
      SUM(MAX_SCORE) AS TOTAL_SCORE
  FROM (
      SELECT
          H.hacker_id,
          H.name,
          S.challenge_id,
          MAX(S.score) AS MAX_SCORE
      FROM
          Hackers H
          JOIN Submissions S ON S.hacker_id = H.hacker_id
      GROUP BY
          H.hacker_id,
          H.name,
          S.challenge_id
  ) AS tmp
  GROUP BY
      hacker_id,
      name
  HAVING
      TOTAL_SCORE > 0
  ORDER BY
      TOTAL_SCORE DESC,
      hacker_id;
  