LeetCode數據庫題之596

    這裏是查詢class,課程和人是多對1的關係所以我的sql是這麼寫的 select class from courses group by class having count(distinct student) >=5 還有一種寫法結果一樣但是是錯誤的, select class from courses group by class having count(*) >=5  這種情況可

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