再加100分，共200, 请高手救急

[needanothercoder]

回答了以下帖子，200分全给，回答部分酌情给分
http://topic.csdn.net/u/20110327/13/b7b4ec1d-f9f1-40c6-b369-fc5ef2c99bca.html?94549

[叶子]

楼下的来解决一下

[快溜]

楼下解决，我打完这把dota

[叶子]

--3.用SQL查询语句描述下列查询：学生“李勇”所选修的课程名。
select distinct Cname from [SC],[Student],[Course]
where [Student].Sname='李勇'

--4.用SQL语句：统计每门课程的选课人数
select c#,count(S#) from [SC] group by C#; 

[叶子]

这个貌似是大二的时候《数据库原理》的课后习题
我一题我也不确定了，楼下可以更正：
ΠC# (σS#='S2'(SXSC))

[叶子]

CREATE TABLE [dbo].[SC](
	[S#] [varchar](10) COLLATE Chinese_PRC_CI_AS NOT NULL,
	[C#] [varchar](10) COLLATE Chinese_PRC_CI_AS NOT NULL,
	[score] [decimal](18, 1) NULL,
	CONSTRAINT [PK_SC] PRIMARY KEY CLUSTERED ([S#] ASC,[C#] ASC),
	CONSTRAINT [FK_SC_Student] FOREIGN KEY([S#]) REFERENCES [dbo].[S] ([S#])
)

第二题，自己填空就可以了

[Oraclers]

1.
πC#(σS.S#=SC.S#^S.S#=’S2’(S×SC))
2.
CONSTRAINT PK_S_C PRIMARY KEY (S#,C#)
CONSTRAINT FK_S FOREIGN KEY (S#) REFERENCES S(S#)
3.
select C.CNAME
from S join SC on S.S#=SC.S# join C on SC.C#=C.C#
where S.SNAME='李勇'
4.
select SC.C#,count(SC.S#) as 人数
from SC
group by SC.C#

给分吧！

[叶子]

[Quote=引用 6 楼 oraclers 的回复:]
1.
πC#(σS.S#=SC.S#^S.S#=’S2’(S×SC))
2.
CONSTRAINT PK_S_C PRIMARY KEY (S#,C#)
CONSTRAINT FK_S FOREIGN KEY (S#) REFERENCES S(S#)
3.
select C.CNAME
from S join SC on S.S#=SC.S# join C on SC.C#=C.C……
[/Quote]
支持一下，第一问我写错了，选择的时候少个条件，还没加表名，投影的时候表名也最好补充上。

[rucypli]

考试题。。。

[dawugui]

http://topic.csdn.net/u/20100517/17/b2ab9d5e-73a2-4f54-a7ec-40a5eabd8621.html

/*
标题：一个项目涉及到的50个Sql语句(整理版)
作者：爱新觉罗.毓华(十八年风雨，守得冰山雪莲花开)
时间：2010-05-10
地点：重庆航天职业学院
说明：以下五十个语句都按照测试数据进行过测试，最好每次只单独运行一个语句。
问题及描述：
--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)
go

--1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数
--1.1、查询同时存在"01"课程和"02"课程的情况
select a.* , b.score [课程'01'的分数],c.score [课程'02'的分数] from Student a , SC b , SC c 
where a.S# = b.S# and a.S# = c.S# and b.C# = '01' and c.C# = '02' and b.score > c.score
--1.2、查询同时存在"01"课程和"02"课程的情况和存在"01"课程但可能不存在"02"课程的情况(不存在时显示为null)(以下存在相同内容时不再解释)
select a.* , b.score [课程"01"的分数],c.score [课程"02"的分数] from Student a 
left join SC b on a.S# = b.S# and b.C# = '01'
left join SC c on a.S# = c.S# and c.C# = '02'
where b.score > isnull(c.score,0)

--2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
--2.1、查询同时存在"01"课程和"02"课程的情况
select a.* , b.score [课程'01'的分数],c.score [课程'02'的分数] from Student a , SC b , SC c 
where a.S# = b.S# and a.S# = c.S# and b.C# = '01' and c.C# = '02' and b.score < c.score
--2.2、查询同时存在"01"课程和"02"课程的情况和不存在"01"课程但存在"02"课程的情况
select a.* , b.score [课程"01"的分数],c.score [课程"02"的分数] from Student a 
left join SC b on a.S# = b.S# and b.C# = '01'
left join SC c on a.S# = c.S# and c.C# = '02'
where isnull(b.score,0) < c.score

--3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
select a.S# , a.Sname , cast(avg(b.score) as decimal(18,2)) avg_score
from Student a , sc b
where a.S# = b.S#
group by a.S# , a.Sname
having cast(avg(b.score) as decimal(18,2)) >= 60 
order by a.S#

--4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
--4.1、查询在sc表存在成绩的学生信息的SQL语句。
select a.S# , a.Sname , cast(avg(b.score) as decimal(18,2)) avg_score
from Student a , sc b
where a.S# = b.S#
group by a.S# , a.Sname
having cast(avg(b.score) as decimal(18,2)) < 60 
order by a.S#
--4.2、查询在sc表中不存在成绩的学生信息的SQL语句。
select a.S# , a.Sname , isnull(cast(avg(b.score) as decimal(18,2)),0) avg_score
from Student a left join sc b
on a.S# = b.S#
group by a.S# , a.Sname
having isnull(cast(avg(b.score) as decimal(18,2)),0) < 60 
order by a.S#

--5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
--5.1、查询所有有成绩的SQL。
select a.S# [学生编号], a.Sname [学生姓名], count(b.C#) 选课总数, sum(score) [所有课程的总成绩]
from Student a , SC b 
where a.S# = b.S# 
group by a.S#,a.Sname 
order by a.S#
--5.2、查询所有(包括有成绩和无成绩)的SQL。
select a.S# [学生编号], a.Sname [学生姓名], count(b.C#) 选课总数, sum(score) [所有课程的总成绩]
from Student a left join SC b 
on a.S# = b.S# 
group by a.S#,a.Sname 
order by a.S#

--6、查询"李"姓老师的数量 
--方法1
select count(Tname) ["李"姓老师的数量] from Teacher where Tname like N'李%'
--方法2
select count(Tname) ["李"姓老师的数量] from Teacher where left(Tname,1) = N'李'
/*
"李"姓老师的数量   
----------- 
1
*/

--7、查询学过"张三"老师授课的同学的信息 
select distinct Student.* from Student , SC , Course , Teacher 
where Student.S# = SC.S# and SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N'张三'
order by Student.S#

--8、查询没学过"张三"老师授课的同学的信息 
select m.* from Student m where S# not in (select distinct SC.S# from SC , Course , Teacher where SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N'张三') order by m.S#

--9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
--方法1
select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = '01' and exists (Select 1 from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = '02') order by Student.S#
--方法2
select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = '02' and exists (Select 1 from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = '01') order by Student.S#
--方法3
select m.* from Student m where S# in
(
  select S# from
  (
    select distinct S# from SC where C# = '01'
    union all
    select distinct S# from SC where C# = '02'
  ) t group by S# having count(1) = 2 
)
order by m.S#

--10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
--方法1
select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = '01' and not exists (Select 1 from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = '02') order by Student.S#
--方法2
select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = '01' and Student.S# not in (Select SC_2.S# from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = '02') order by Student.S#

--11、查询没有学全所有课程的同学的信息 
--11.1、
select Student.*
from Student , SC 
where Student.S# = SC.S# 
group by Student.S# , Student.Sname , Student.Sage , Student.Ssex having count(C#) < (select count(C#) from Course) 
--11.2
select Student.*
from Student left join SC 
on Student.S# = SC.S# 
group by Student.S# , Student.Sname , Student.Sage , Student.Ssex having count(C#) < (select count(C#) from Course) 

--12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息 
select distinct Student.* from Student , SC where Student.S# = SC.S# and SC.C# in (select C# from SC where S# = '01') and Student.S# <> '01'

--13、查询和"01"号的同学学习的课程完全相同的其他同学的信息 
select Student.* from Student where S# in
(select distinct SC.S# from SC where S# <> '01' and SC.C# in (select distinct C# from SC where S# = '01') 
group by SC.S# having count(1) = (select count(1) from SC where S#='01')) 

--14、查询没学过"张三"老师讲授的任一门课程的学生姓名 
select student.* from student where student.S# not in 
(select distinct sc.S# from sc , course , teacher where sc.C# = course.C# and course.T# = teacher.T# and teacher.tname = N'张三')
order by student.S#

--15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩 
select student.S# , student.sname , cast(avg(score) as decimal(18,2)) avg_score from student , sc 
where student.S# = SC.S# and student.S# in (select S# from SC where score < 60 group by S# having count(1) >= 2)
group by student.S# , student.sname

--16、检索"01"课程分数小于60，按分数降序排列的学生信息
select student.* , sc.C# , sc.score from student , sc 
where student.S# = SC.S# and sc.score < 60 and sc.C# = '01'
order by sc.score desc  

--17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
--17.1 SQL 2000 静态 
select a.S# 学生编号 , a.Sname 学生姓名 ,
       max(case c.Cname when N'语文' then b.score else null end) [语文],
       max(case c.Cname when N'数学' then b.score else null end) [数学],
       max(case c.Cname when N'英语' then b.score else null end) [英语],
       cast(avg(b.score) as decimal(18,2)) 平均分
from Student a 
left join SC b on a.S# = b.S#
left join Course c on b.C# = c.C#
group by a.S# , a.Sname
order by 平均分 desc
--17.2 SQL 2000 动态 
declare @sql nvarchar(4000)
set @sql = 'select a.S# ' + N'学生编号' + ' , a.Sname ' + N'学生姓名'
select @sql = @sql + ',max(case c.Cname when N'''+Cname+''' then b.score else null end) ['+Cname+']'
from (select distinct Cname from Course) as t
set @sql = @sql + ' , cast(avg(b.score) as decimal(18,2)) ' + N'平均分' + ' from Student a left join SC b on a.S# = b.S# left join Course c on b.C# = c.C#
group by a.S# , a.Sname order by ' + N'平均分' + ' desc'
exec(@sql)
--17.3 有关sql 2005的动静态写法参见我的文章《普通行列转换(version 2.0)》或《普通行列转换(version 3.0)》。

[xrongzhen]

[Quote=引用 2 楼 ssp2009 的回复:]
楼下解决，我打完这把dota
[/Quote]

+++

[fanzhouqi]

蛋疼不想回答

[xrongzhen]

--3.用SQL查询语句描述下列查询：
--学生“李勇”所选修的课程名。

select * from Course where C# in(select C# from Student a left join SC b on a.S#=b.S# and a.SName = '李勇') 

select * 
from SC a
left join Student b on a.S#=b.S#
left join Course c on a.C#=c.C#
where b.SName='李勇'

--4.用SQL语句：
--统计每门课程的选课人数
select C# ,count(*) as '课程选课人数' from  SC
group by C# 

select a.C#,max(b.CName) as '课程名' ,count(*) as '课程选课人数' from  SC a,Course b where a.C# = b.C# 
group by a.C# 

[gogodiy]

这些个考试题啊，习题什么的，万变不离dawugui发的这50题～～～