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https://www.hackerrank.com/challenges/challenges/problem Challenges | HackerRank Print the total number of challenges created by hackers. www.hackerrank.com 1. 성공한 코드 SELECT Hackers.hacker_id , name , COUNT(challenge_id) challenges_created FROM Hackers INNER JOIN Challenges ON Hackers.hacker_id = Challenges.hacker_id GROUP BY hacker_id, name HAVING challenges_created = ( SELECT MAX(tmp1.challeng..