SQL面试题
Student(S#,Sname,Sage,Ssex) 学生表 S#:学号;Sname:学生姓名;Sage:学生年龄;Ssex:学生性别
Course(C#,Cname,T#) 课程表 C#:课程编号;Cname:课程名字;T#:教师编号
SC(S#,C#,score) 成绩表 S#:学号;C#,课程编号;score:成绩
Teacher(T#,Tname) 教师表 T#:教师编号; Tname:教师名字
1、查询“001”课程比“002”课程成绩高的所有学生的学号;
select a.S#
from (select s#,score from SC where C#='001') a,
(select s#,score from SC where C#='002') b
where a.score>b.score and a.s#=b.s#;
2、查询平均成绩大于60分的同学的学号和平均成绩;
select S#,avg(score)
from sc
group by S# having avg(score) > 60;
3、查询所有同学的学号、姓名、选课数、总成绩;
select Student.S#,Student.Sname,count(SC.C#),sum(score)
from Student left Outer join SC on Student.S#=SC.S#
group by Student.S#,Sname
4、查询姓“李”的老师的个数;
select count(distinct(Tname))
from Teacher
where Tname like '李%';
5、查询没学过“叶平”老师课的同学的学号、姓名;
select Student.S#,Student.Sname
from Student
where S# not in (select distinct( SC.S#) from SC,Course,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平');
6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名;
select Student.S#,Student.Sname from Student,SC
where Student.S#=SC.S# and SC.C#='001'and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#='002');
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名;
a、查询“叶平”老师所教的所有课
select C# from Course,Teacher where Teacher.T#=Course.T# and Tname='叶平' =》AAA
b、select Student.S#,Student.name from Student left Outer join SC on Student.S#=SC.S# and SC.C# in (AAA)