Question

24.查询学生总人数 用sql语言编写

1. 查询选修了课程的学生人数2. 计算1号课程的学生平均成绩3. 查询选修1号课程的学生最高分数4. 查询学生200215012选修课程的总学分数连接查询：5. 查询每 个学生及其选修课程的情况6. 查询每一门课的间接先修课（即先修课的先修课）7. 查询选修2号课程且成绩在90分以上的所有学生的学号，姓名GROUP BY 子句32. 求各个课程号及相应的选课人数33.查询选修了3门以上课程的学生学号嵌套查询：34.查询与“刘晨”在同一个系学习的学生35.查询选修了课程名为“信息系统”的学生的学号和姓名36.查询其他系中比计算机科学系某一学生年龄小的学生姓名和年龄37.查询其他系中经计算机科学系所有学生年龄都小的学生姓名及年龄带有EXISTS谓词的子查询：38.查询所有选修了1号课程的学生姓名39.查询没有选修1号课程的学生姓名

Answer 1

最好拿个表出来，不然写了你们不容易分析懂

Answer 2

你的表结构是什么样的？

Answer 3

1\select count(*) from Student2\select count(*) from SC group by Sno3\select avg(s.Grade) from Student t,SC s where t.Sdept = 'CS' and t.Sno = s.Sno4\select max(Grade) from SC where Cno = '1'
5\select Sum(c.Ccredit) from SC s,Course c where s.Sno = '200215012' and s.Cno = c.Con
6\select s.Sno,s.Sname,s.Ssex,s.Sage,s.Sdept,c.Cno,C.Cname,C.Cpno,c.Ccredit form SC sc,Course c,Student s where s.Sno = sc.Sno and c.Cno = sc.Cno7,select cname form course where spon in(select cname from selectcourse cpon=cno) 8\select t.Sno,t.Sname from Student t,SC s where s.Cno = '2' and s.Grade > 90 and s.Sno = t.Sno
32\select Cno,count(0) from SC group by Cno
33\select Sno from SC cc where (select count(0) from SC c where c.Sno = cc.Sno group by Sno ) > 3
34\select * from Student t where t.Sdept = (select tt.Sdept from Student tt where tt.Sname = '刘晨')