查询学生的学号，姓名，选修课程号和课程成绩
A: select sid,sname,cid,grade from student,sc where student.sid=sc.sid
B: select * from student,sc where student.sid=sc.sid
C: select sid,sname,cid,cname from student,course
D: select sid,sname,cid,cname from student,sc
A: select sid,sname,cid,grade from student,sc where student.sid=sc.sid
B: select * from student,sc where student.sid=sc.sid
C: select sid,sname,cid,cname from student,course
D: select sid,sname,cid,cname from student,sc
举一反三
- 按照学号进行分组，统计学生的平均成绩（） A: select sid, avg(grade) from student group by cid B: select sid, avg(grade) from student group by sid C: select sid, avg(grade) from sc group by sid D: select sid, avg(grade) from sc group by cid
- 查询成绩在60分以上的学生的信息及其选课的课程号和成绩 A: select student.*,cid,grade from student,sc where student.sid=sc.sid and grade>=60 B: select * from student,sc where student.sid=sc.sid where grade>=60 C: select * from student,sc where student.sid=sc.sid where student.sid=sc.sid D: select * from student,course where grade>=60
- 按课程号分类，统计相应的选课人数（） A: select cid, count(distinct sid) from sc group by cid B: select cid, count(*) from student group by cid C: select cid, count(distinct cid) from sc group by cid D: select cid, count(distinct sid) from student group by cid
- 按照学号进行分组，统计学生的平均成绩，且平均分按降序排列 A: select sid, avg(grade) from sc group by sid order by avg(grade) desc B: select sid, avg(grade) from sc group by cid order by avg(grade) desc C: select sid, avg(grade) from student group by sid order by avg(grade) desc D: select sid, avg(grade) from student group by cid order by avg(grade)
- 查询选修了2门课程以上的学生学号（） A: select sid,count(*) from sc group by sid having count(*)>=2 B: select sid,count(*) from sc group by sid where count(*)>=2 C: select sid,count(*) from sc where count(*)>=2 group by sid D: select sid,count(*) from sc group by cid having count(*)>=2