Leetcode - 596. Classes More Than 5 Students

Indo Yoon -

문제

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LeetCode

정답

처음에는 이렇게 풀었는데...

SELECT class
FROM (SELECT class, COUNT(*) AS counts FROM Courses GROUP BY class) AS C
WHERE counts > 4

간단한 문제인데 이렇게 안해도 되지 않을까 해서 다른 답변을 찾아봤더니 HAVING 으로 간단하게 풀 수 있었다. 자주 안쓰다 보니 까먹었는데 그룹화했을 때 조건을 달 때는 HAVING 을 사용하자.

SELECT class
FROM Courses
GROUP BY class
HAVING COUNT(class) > 4