--------------------------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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问题二十三：统计打印各科成绩各分数段人数：课程ID，课程名称，[100-85]，[85-70]，[70-60]，[<60]
SELECT sc.S_CId "课程ID", course.Cname "课程名称", SUM(CASE WHEN sc.Score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) "[100-85]", SUM(CASE WHEN sc.Score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) "[85-70]", SUM(CASE WHEN sc.Score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) "[70-60]", SUM(CASE WHEN sc.Score<60 THEN 1 ELSE 0 END) "[<60]" FROM sc,course where sc.S_CId=course.CId GROUP BY sc.S_CId;
答案仅供参考，不一定完全正确，若发现错误或有更好的，欢迎评论，互相交流，一起成长！！！