Question

用SQL语句查询所有学生（包括未选课的学生）的学号、姓名（SName）、该学生所选课程的平均分。提示：用外

Answer 1

SELECT 学号 = S.SNo,
姓名 = SName,
平均分 = AVG(Score)
FROM Student S
LEFT OUTER JOIN SC
ON S.SNo=SC.SNo
GROUP BY S.SNo,SName

Answer 2

select sno,sname,avg(score) from sc,student
where sc.sno=student.sno order by sno;

Answer 3

select sno,sname,avg(score) from sc,student where sc.sno=student.sno order by sname;