50个SQL语句(MySQL版) 问题二十五

--------------------------表结构--------------------------

student(StuId,StuName,StuAge,StuSex) 学生表

teacher(TId,Tname) 教师表

course(CId,Cname,C_TId) 课程表

sc(SId,S_CId,Score) 成绩表

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问题二十五：查询各科成绩前三名的记录(不考虑成绩并列情况)

SELECT * FROM
(SELECT s1.S_CId,s1.Score,COUNT(DISTINCT s2.Score) Rank
FROM sc AS s1
INNER JOIN sc AS s2
ON s1.S_CId=s2.S_CId AND s1.Score<s2.Score
GROUP BY s1.S_CId,s1.Score) score
WHERE score.Rank>=1 AND score.Rank<=3 
GROUP BY score.S_CId,score.Rank;

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