https://www.hackerrank.com/challenges/challenges/submissions/database/331359810 SELECT h.hacker_id , h.name , count(*) Challenges_created FROM Challenges c INNER JOIN Hackers h ON h.hacker_id = c.hacker_id GROUP BY h.hacker_id, h.name HAVING Challenges_created = (SELECT MAX(Challenges_created) --Challeges_created MAX 값이 50인 것 FROM( SELECT hacker_id , count(*) Challenges_created FROM Challenges G..