Untitled

SELECT 
submission_date,
(SELECT COUNT(DISTINCT hacker_id)  
 FROM submissions s2  
 WHERE s2.submission_date = s1.submission_date AND 
       (SELECT COUNT(DISTINCT s3.submission_date) 
        FROM Submissions s3 
        WHERE s3.hacker_id = s2.hacker_id AND s3.submission_date < s1.submission_date) 
       = DATEDIFF(s1.submission_date , '2016-03-01')) ,
(SELECT hacker_id  
 FROM submissions s2 
 WHERE s2.submission_date = s1.submission_date 
 GROUP BY hacker_id ORDER BY COUNT(submission_id) DESC , hacker_id limit 1) AS max_sub,
(SELECT name 
 FROM hackers 
 WHERE hacker_id = max_sub)
FROM (SELECT DISTINCT submission_date FROM submissions) s1
GROUP BY submission_date