• 2022-06-07
    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
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    • 0

      【单选题】假设订单表 orders 用于存储订单信息, cid 代表客户编号, money 代表单次订购额,现要查询每个客户的订购次数和每个客户的订购总金额,则下列() SQL 语句可以返回正确的结果。 A. select cid,count(distinct(cid)),sum(money) from ordersgroup by cid B. select cid , count(distinct(cid)) , sum(money) fromorders order by cid C. select cid , count(cid) , sum(money) from orders orderby cid D. select cid , count(cid) , sum(money) from orders groupby cid

    • 1

      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

    • 2

      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)

    • 3

      查询选修了a001号课程且成绩在60分以上的所有学生 A: select * from course where cid=’a001’ and grade>=60 B: select * from student where cid=’a001’ and grade>=60 C: select * from sc where cid=’a001’ D: select * from sc where cid=’a001’ and grade>=60

    • 4

      检索选课人数少于4人的课程号。正确的SQL语句是( ) A: SELECT CNO FROM SC WHERE COUNT(*)<;4 B: SELECT CNO FROM SC GROUP BY CNO HAVING COUNT(*)<;4 C: SELECT DISTINCT CNO FROM SC ORDER BY CNO D: SELECT CNO FROM SC WHERE COUNT(CNO)<;4