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https://www.hackerrank.com/challenges/challenges/problem?isFullScreen=true Challenges | HackerRank Print the total number of challenges created by hackers. www.hackerrank.com 1. 에러난 코드 SELECT H.hacker_id, H.name, COUNT(C.challenge_id) as challenges_created FROM Hackers H INNER JOIN Challenges C ON H.hacker_id = C.hacker_id WHERE MAX(challenges_created) OR COUNT(challenges_created) = 1 #문제1 GROUP..