SELECT c.contest_id, c.hacker_id, c.name, 
       SUM(s.total_submissions) AS total_submissions, 
       SUM(s.total_accepted_submissions) AS total_accepted_submissions, 
       SUM(v.total_views) AS total_views, 
       SUM(v.total_unique_views) AS total_unique_views 
FROM Contests c 
JOIN Colleges cl ON c.contest_id = cl.contest_id 
JOIN Challenges ch ON ch.college_id = cl.college_id 
JOIN View_Stats v ON v.challenge_id = ch.challenge_id 
JOIN Submission_Stats s ON s.challenge_id = ch.challenge_id 
GROUP BY c.contest_id, c.hacker_id, c.name 
HAVING SUM(s.total_submissions) + SUM(s.total_accepted_submissions) + SUM(v.total_views) + SUM(v.total_unique_views) > 0 
ORDER BY c.contest_id