经典SQL面试题
(1)
--1.学生表
Student(S#,Sname,Sage,Ssex) --S# 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
--2.课程表
Course(C#,Cname,T#) --C# --课程编号,Cname 课程名称,T# 教师编号
--3.教师表
Teacher(T#,Tname) --T# 教师编号,Tname 教师姓名
--4.成绩表
SC(S#,C#,score) --S# 学生编号,C# 课程编号,score 分数
*/
--创建测试数据
create table Student(S# varchar(10),Sname nvarchar(10),Sage datetime,Ssex nvarchar(10)) insert into Student values('01' , N'赵雷' , '1990-01-01' , N'男') insert into Student values('02' , N'钱电' , '1990-12-21' , N'男') insert into Student values('03' , N'孙风' , '1990-05-20' , N'男') insert into Student values('04' , N'李云' , '1990-08-06' , N'男') insert into Student values('05' , N'周梅' , '1991-12-01' , N'女') insert into Student values('06' , N'吴兰' , '1992-03-01' , N'女') insert into Student values('07' , N'郑竹' , '1989-07-01' , N'女') insert into Student values('08' , N'王菊' , '1990-01-20' , N'女') create table Course(C# varchar(10),Cname nvarchar(10),T# varchar(10)) insert into Course values('01' , N'语文' , '02') insert into Course values('02' , N'数学' , '01') insert into Course values('03' , N'英语' , '03') create table Teacher(T# varchar(10),Tname nvarchar(10)) insert into Teacher values('01' , N'张三') insert into Teacher values('02' , N'李四') insert into Teacher values('03' , N'王五') create table SC(S# varchar(10),C# varchar(10),score decimal(18,1)) insert into SC values('01' , '01' , 80) insert into SC values('01' , '02' , 90) insert into SC values('01' , '03' , 99) insert into SC values('02' , '01' , 70) insert into SC values('02' , '02' , 60) insert into SC values('02' , '03' , 80) insert into SC values('03' , '01' , 80) insert into SC values('03' , '02' , 80) insert into SC values('03' , '03' , 80) insert into SC values('04' , '01' , 50) insert into SC values('04' , '02' , 30) insert into SC values('04' , '03' , 20) insert into SC values('05' , '01' , 76) insert into SC values('05' , '02' , 87) insert into SC values('06' , '01' , 31) insert into SC values('06' , '03' , 34) insert into SC values('07' , '02' , 89) insert into SC values('07' , '03' , 98)
--1、查询“01”课程比“02”课程成绩高的所有学生的学号；
select a.S#,a.score,b.score from
(select * from SC where SC.C#='01') a,
(select * from SC where SC.C#='02') 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 SC.S#,AVG(SC.score) avgScore from SC group by SC.S# having AVG(SC.score)>603、查询所有同学的学号、姓名、选课数、总成绩；
select SC.S#,Student.Sname,COUNT(SC.C#) 选课数, AVG(SC.score) 平均分
from SC left join Student on SC.S#=Student.S#
group by SC.S#,Student.Sname
order by SC.S#4、查询姓“李”的老师的个数；
select COUNT(distinct(Teacher.TName)) from Teacher where Teacher.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 Student.S# not in( select SC.S# from Course,SC,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平' )6、查询学过“01”并且也学过编号“02”课程的同学的学号、姓名；
select *, Student.S#,Student.Sname from Student left join SC on Student.S#=SC.S# where SC.C# ='01' and exists ( select * from SC SC_1 where SC_1.S#=Student.S# and SC_1.C#='02' )9、查询没有学全所有课的同学的学号、姓名；
select Student.S#,Student.Sname from Student,SC where Student.S#=SC.S# group by Student.S#,Student.Sname having COUNT(SC.C#)< (select COUNT(Course.C#) from Course)