해커랭크(HackerRank) SQL 문제풀이 - Contest Leaderboard

SELECT H.HACKER_ID,H.NAME,SUB1.SCO
    FROM HACKERS H
    JOIN (SELECT SUB.HACKER_ID AS HID,SUM(MS) AS SCO
            FROM(SELECT HACKER_ID,CHALLENGE_ID,MAX(SCORE) AS MS
                    FROM SUBMISSIONS
                    GROUP BY HACKER_ID,CHALLENGE_ID) SUB
            GROUP BY SUB.HACKER_ID
            HAVING SCO!=0) SUB1 ON H.HACKER_ID=SUB1.HID
    ORDER BY 3 DESC,1;