SQL--上机一使用分组查询学生相关信息

--查询每个年级的总学时数,并按照升序排列
SELECT gradeId,SUM(ClassHour)as 总学时
FROM Subject
GROUP BY GradeId
order by SUM(ClassHour)
--查询每个参加考试的学员平均分
SELECT StudentNo,AVG(StudentResult)as 平均分
FROM Result
group by StudentNo
--查询每门课程的平均分,并按照降序排列
SELECT SubjectId,AVG(StudentResult) as 平均分
FROM Result
group by SubjectId
order by AVG(StudentResult) desc
--查询每个学生参加的所有考试的总分,并按照降序排列
SELECT StudentNo,SUM(StudentResult)as 总分
FROM Result
group by StudentNo
order by SUM(StudentResult) desc