统计各科成绩各分数段人数：课程编号，课程名称，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比

统计各科成绩各分数段人数：课程编号，课程名称，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比 select sc.CId, sum(case when sc.score >=85 then 1 else 0 end) as num_100_85, sum(case when sc.score >=70 and sc.score <85 0 1 then else end) as num_85_70, sum(case when sc.score>= 60 and sc.score < 70 then 1 else 0 end) as num_70_60, sum(case when sc.score < 60 then 1 else 0 end) as num_60_0, sum(case when sc.score >=85 then 1 else 0 end)/count(*) as p_100_85, sum(case when sc.score >=70 and sc.score <85 0 1 then else end) count(*) as p_85_70, sum(case when sc.score>= 60 and sc.score < 70 then 1 else 0 end)/count(*) as p_70_60, sum(case when sc.score < 60 then 1 else 0 end)/count(*) as p_60_0 from sc group by sc.CId

B、SELECT课程名称,开课院系,COUNT(学号)选修人数FROM学生成绩,课程WHERE课程.课程编号=学生成绩.课程编号GROUPBY学生成绩.学HAVINGCOUNT(*)<=2ORDERBYCOUNT(学号)

C、SELECT课程名称,开课院系,COUNT(学号)AS选修人数;

FROM学生成绩,课程WHERE课程.课程编号=学生成绩.课程编号;

GROUPBY课程名称HAVINGCOUNT(学号)<=2ORDERBY选修人数

D、SELECT课程名称,开课院系,COUNT(学号)AS选修人数;

FROM学生成绩,课程HAVINGCOUNT(课程编号)<=2GROUPBY课程名称ORDERBY选修人数

查询各科成绩最高分、最低分和平均分： 以如下形式显示： -- 课程 ID，课程 name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率 -- 及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90 -- 要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列 select sc.CId, max(sc.score) as '最高分', min(sc.score) as '最低分', avg(sc.score) as '平均分', count(*) as '选修人数', sum(case when sc.score >= 60 then 1 else 0 end)/count(*) as '及格率', sum(case when sc.score >= 70 and sc.score < 80 then 1 else 0 end)/count(*) as '中等率', sum(case when sc.score >= 80 and sc.score < 90 then 1 else 0 end)/count(*) as '优良率', sum(case when sc.score >= 90 then 1 else 0 end)/count(*) as '优秀率' from sc group by sc.CId order by count(*) DESC, sc.CId ASC

学生(学号C(8),姓名C(12),性别C(2),出生日期D,院系C(8))

课程(课程编号C(4),课程名称C(10),开课院系C(8))

学生成绩(学号C(8),课程编号C(4),成绩工)

查询每门课程的最高分，要求得到的信息包括课程名称和分数。正确的命令是(  )。

A．SELECT 课程名称,SUM(成绩)AS 分数 FROM 课程,学生成绩;

WHERE 课程.课程编号=学生成绩.课程编号;

GROUP BY 课程名称

B．SELECT 课程名称,MAX(成绩) 分数 FROM 课程,学生成绩;

WHERE 课程.课程编号=学生成绩.课程编号;

GROUP BY 课程名称

C．SELECT 课程名称,SUM(成绩) 分数 FROM 课程,学生成绩;

GROUP BY 课程.课程编号

D．SELECT 课程名称,MAX(成绩)AS 分数 FROM 课程,学生成绩;

WHERE 课程.课程编号=学生成绩.课程编号;

GROUP BY 课程编号

A、数与代数

B、图形与几何

C、统计与概率

D、综合与实践