select submissions.hacker_id,hackers.name from hackers inner join submissions on hackers.hacker_id=submissions.hacker_id inner join challenges on challenges.challenge_id=submissions.challenge_id inner join difficulty on challenges.difficulty_level=difficulty.difficulty_level where difficulty.score=submissions.score group by submissions.hacker_id,hackers.name having count(hackers.name)>1 order by count(hackers.name) desc,submissions.hacker_id asc

Plz someone help me ,what's wrong in this query. select a.hacker_id, a.name from hackers a join submissions b on a.hacker_id= b.hacker_id where b.challenge_id in (select a.challenge_id from challenges a join difficulty b on a.difficulty_level=b.difficulty_level) and b.score in (select a.score from difficulty a join challenges b on a.difficulty_level=b.difficulty_level) group by a.hacker_id having count(a.hacker_id)>1 order by count(a.hacker_id) desc, a.hacker_id asc

MYSQL:

select s.hacker_id, h.name from submissions as s 
			inner join Challenges as c on s.challenge_id=c.challenge_id
			inner join Difficulty as d on d.difficulty_level=c.difficulty_level
			inner join Hackers as h on h.hacker_id=s.hacker_id 
where d.score=s.score 
group by s.hacker_id,h.name having count(*)>1 
order by count(*) desc, s.hacker_id;

MySQL:

SELECT hacker_id, name FROM (
    SELECT H.hacker_id, name, COUNT(challenge_id) AS ct
    FROM Submissions AS S
    LEFT JOIN Hackers AS H USING (hacker_id)
    LEFT JOIN Challenges USING (challenge_id)
    LEFT JOIN Difficulty AS D USING (difficulty_level)
    WHERE S.score = D.score
    GROUP BY H.hacker_id, name HAVING ct > 1
    ORDER BY ct DESC, H.hacker_id ASC
) AS rankings;

select h.Hacker_ID, Name from submissions s join challenges c on s.challenge_id=c.challenge_id join difficulty d on d.difficulty_level=c.difficulty_level join Hackers h on s.hacker_id=h.hacker_id

where s.score=d.score group by h.Hacker_ID, Name having count(submission_id)>1 order by count(submission_id) desc,h.Hacker_ID