MySQL练习题参考答案

2、查询“生物”课程比“物理”课程成绩高的所有学生的学号；

select A.student_id from 
(select student_id,num from score LEFT JOIN course on score.course_id=course.cid WHERE course.cname="生物") as A
INNER JOIN
(select student_id,num from score LEFT JOIN course on score.course_id=course.cid WHERE course.cname="物理") as B
ON A.student_id=B.student_id WHERE A.num > B.num

 3、查询平均成绩大于60分的同学的学号、名字和平均成绩；

select student.sid,student.sname,B.numname from 
(select student_id,avg(num) as numname from score GROUP BY student_id HAVING AVG(num)>60) as B
LEFT JOIN student on B.student_id=student.sid

4、查询所有同学的学号、姓名、选课数、总成绩；

SELECT student_id,student.sname,COUNT(course_id),SUM(num) from score LEFT JOIN student on score.student_id=student.sid GROUP BY student_id

5、查询姓“李”的老师的个数；

select * from teacher WHERE tname like "李%"

6、查询没学过“李平”老师课的同学的学号、姓名；

SELECT student.sid,student.sname from student WHERE student.sid not in (
SELECT student_id from score WHERE score.course_id in 
(select course.cid from course LEFT JOIN teacher on course.teacher_id=teacher.tid WHERE teacher.tname="李平老师") GROUP BY student_id)

MySQL练习题参考答案

标签：rom   for   bsp   opened   cap   localhost   nod   技术分享   nsf