举例说明：
一个题目涉及到的50个Sql语句 --（下面表的结构以给出,自己在数据库中建立表.并且添加相应的数据,数据要全面些. 其中Student表中,SId为学生的ID）
表结构:
学生表tblStudent（编号StuId、姓名StuName、年龄StuAge、性别StuSex）
课程表tblCourse（课程编号CourseId、课程名称CourseName、教师编号TeaId）
成绩表tblScore（学生编号StuId、课程编号CourseId、成绩Score）
教师表tblTeacher（教师编号TeaId、姓名TeaName）
问题：
1、查询“001”课程比“002”课程成绩高的所有学生的学号；
Select StuId From tblStudent s1 Where (Select Score From tblScore t1 Where t1.StuId=s1.stuId And t1.CourseId='001')> (Select Score From tblScore t2 Where t2.StuId=s1.stuId And t2.CourseId='002')
2、查询平均成绩大于60分的同学的学号和平均成绩；
Select StuId,Avg(Score) as AvgScore From tblScore Group By StuId Having Avg(Score)>60
3、查询所有同学的学号、姓名、选课数、总成绩；
Select StuId,StuName,SelCourses=(Select Count(CourseId) From tblScore t1 Where t1.StuId=s1.StuId), SumScore=(Select Sum(Score) From tblScore t2 Where t2.StuId=s1.StuId) From tblStudent s1
4、查询姓“李”的老师的个数；
Select Count(*) From tblTeacher Where TeaName like '李%'
5、查询没学过“叶平”老师课的同学的学号、姓名；
Select StuId,StuName From tblStudent Where StuId Not In ( Select StuID From tblScore sc Inner Join tblCourse cu ON sc.CourseId=cu.CourseId Inner Join tblTeacher tc ON cu.TeaId=tc.TeaId Where tc.TeaName='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 StuId,StuName From tblStudent st Where (Select Count(*) From tblScore s1 Where s1.StuId=st.StuId And s1.CourseId='001')>0 And (Select Count(*) From tblScore s2 Where s2.StuId=st.StuId And s2.CourseId='002')>0
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
Select StuId,StuName From tblStudent st Where not exists ( Select CourseID From tblCourse cu Inner Join tblTeacher tc On cu.TeaID=tc.TeaID Where tc.TeaName='叶平' And CourseID not in (Select CourseID From tblScore Where StuID=st.StuID) )
8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；
Select StuId,StuName From tblStudent s1 Where (Select Score From tblScore t1 Where t1.StuId=s1.stuId And t1.CourseId='001')> (Select Score From tblScore t2 Where t2.StuId=s1.stuId And t2.CourseId='002')
9、查询所有课程成绩小于60分的同学的学号、姓名；
Select StuId,StuName From tblStudent st Where StuId Not IN (Select StuId From tblScore sc Where st.StuId=sc.StuId And Score>60)
10、查询没有学全所有课的同学的学号、姓名；
Select StuId,StuName From tblStudent st Where (Select Count(*) From tblScore sc Where st.StuId=sc.StuId)< (Select Count(*) From tblCourse)
11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；
运用连接查询：Select DistInct st.StuId,StuName From tblStudent st Inner Join tblScore sc ON st.StuId=sc.StuId Where sc.CourseId IN (Select CourseId From tblScore Where StuId='1001')
嵌套子查询：Select StuId,StuName From tblStudent Where StuId In (Select Distinct StuId From tblScore Where CourseId In (Select CourseId From tblScore Where StuId='1001'))
12、查询至少学过学号为“1001”同学所有课程的其他同学学号和姓名；
Select StuId,StuName From tblStudent Where StuId In (Select Distinct StuId From tblScore Where CourseId Not In (Select CourseId From tblScore Where StuId='1001')
13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩； (从子查询中获取父查询中的表名，这样也行？？？？)
创建测试表 Select * Into Sc From tblScore go
Update Sc Set Score=(Select Avg(Score) From tblScore s1 Where s1.CourseId=sc.CourseId) Where CourseId IN (Select CourseId From tblCourse cs INNER JOIN tblTeacher tc ON cs.TeaID=tc.TeaID WHERE TeaName ='叶平')
14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；
Select StuID,StuName From tblStudent st Where StuId <> '1002' And Not Exists(Select * From tblScore sc Where sc.StuId=st.StuId And CourseId Not In (Select CourseId From tblScore Where StuId='1002')) And Not Exists(Select * From tblScore Where StuId='1002' And CourseId Not In (Select CourseId From tblScore sc Where sc.StuId=st.StuId))
15、删除学习“叶平”老师课的SC表记录；
Delete From tblScore Where CourseId IN (Select CourseId From tblCourse cs INNER JOIN tblTeacher tc ON cs.TeaId=tc.TeaId Where tc.TeaName='叶平')
16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、'002'号课的平均成绩；
Insert Into tblScore (StuId,CourseId,Score) Select StuId,'002',(Select Avg(Score) From tblScore Where CourseId='002') From tblScore Where StuId Not In (Select StuId From tblScore Where CourseId='003')
17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示：
学生ID,,数据库,企业管理,英语,有效课程数,有效平均分
Select StuId ,数据库=(Select Score From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='数据库' And sc.StuID=st.StuId) ,企业管理=(Select Score From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='企业管理' And sc.StuID=st.StuId) ,英语=(Select Score From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='英语' And sc.StuID=st.StuId) ,有效课程数=(Select Count(Score) From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where (CourseName='数据库' or CourseName='企业管理' or CourseName='英语') And sc.StuID=st.StuId) ,有效平均分=(Select Avg(Score) From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where (CourseName='数据库' or CourseName='企业管理' or CourseName='英语') And sc.StuID=st.StuId) From tblStudent st Order by 有效平均分 Desc
18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
Select CourseId as 课程ID, 最高分=(Select Max(Score) From tblScore sc Where sc.CourseId=cs.CourseId ), 最低分=(Select Min(Score) From tblScore sc Where sc.CourseId=cs.CourseId ) From tblCourse cs
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序 (百分数后如何格式化为两位小数??)
Select 课程ID,平均分,及格率 From (Select CourseId as 课程ID, 平均分=(Select Avg(Score) From tblScore sc Where sc.CourseId=cs.CourseId ), 及格率=Convert(varchar(10),((Select Count(*) From tblScore sc Where sc.CourseId=cs.CourseId And sc.Score>=60)*10000/(Select Count(*) From tblScore sc Where sc.CourseId=cs.CourseId))/100)+'%' From tblScore cs) as tmp Group by 课程ID,平均分,及格率 Order by 平均分, Convert(float,substring(及格率,1,len(及格率)-1)) Desc
20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004）
Select 课程ID=sc.CourseId,课程名称=cs.CourseName,平均成绩=Avg(Score) ,及格率 =Convert(varchar(10),((Select Count(Score) From tblScore Where CourseId=sc.CourseId And Score>=60)*10000/Count(Score))/100.0)+'%' From tblScore sc Inner Join tblCourse cs ON sc.CourseId=cs.CourseId Where sc.CourseId like '00[1234]' Group By sc.CourseId,cs.CourseName
21、查询不同老师所教不同课程平均分从高到低显示
Select 课程ID=CourseId,课程名称=CourseName,授课教师=TeaName,平均成绩=(Select Avg(Score) From tblScore Where CourseId=cs.CourseId) From tblCourse cs Inner Join tblTeacher tc ON cs.TeaId=tc.TeaId Order by 平均成绩 Desc
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004） 格式：[学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩
Select * From ( Select Top 6 学生ID=StuId,学生姓名=StuName ,企业管理=(Select Score From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='企业管理' And sc.StuID=st.StuId) ,马克思=(Select Score From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='马克思' And sc.StuID=st.StuId) ,UML=(Select Score From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='UML' And sc.StuID=st.StuId) ,数据库=(Select Score From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='数据库' And sc.StuID=st.StuId) ,平均成绩=(Select Avg(Score) From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where (CourseName='数据库' or CourseName='企业管理' or CourseName='UML'or CourseName='马克思') And sc.StuID=st.StuId) ,排名=Row_Number() Over(Order by(Select Avg(Score) From tblScore sc Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where (CourseName='数据库' or CourseName='企业管理' or CourseName='UML'or CourseName='马克思') And sc.StuID=st.StuId) DESC) From tblStudent st Order by 排名 ) as tmp Where 排名 between 3 And 6
23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]
Select 课程ID=CourseId, 课程名称=CourseName ,[100-85]=(Select Count(*) From tblScore sc Where CourseId=cs.CourseId And Score between 85 And 100) ,[85-70]=(Select Count(*) From tblScore sc Where CourseId=cs.CourseId And Score between 70 And 84) ,[70-60]=(Select Count(*) From tblScore sc Where CourseId=cs.CourseId And Score between 60 And 69) ,[<60]=(Select Count(*) From tblScore sc Where CourseId=cs.CourseId And Score <60) From tblCourse cs
24、查询学生平均成绩及其名次
Select 学号=st.StuId, 姓名=StuName,平均成绩=sc.AvgScore,名次=(Dense_Rank() Over(Order by sc.AvgScore Desc)) From tblStudent st Inner Join (Select StuId,Avg(Score) as AvgScore From tblScore Group by StuId) as sc On sc.StuId=st.StuId Order by 学号
25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
Select 学号=StuId,课程号=CourseId,分数=Score From (Select Row_Number() Over(order by CourseId,Score Desc) as i,* From tblScore) as tmp --得到一个临时的排名表,其中i表示编号 Where i In ( Select Top 3 i From (Select Row_Number() Over(order by CourseId,Score Desc) as i,* From tblScore) as t1 Where t1.CourseId=tmp.CourseId )
26、查询每门课程被选修的学生数
Select 课程ID=CourseId,选修人数=(Select Count(*) From (Select Distinct StuId From tblScore Where CourseId=cs.CourseId) as tmp) From tblCourse cs
27、查询出只选修了一门课程的全部学生的学号和姓名
Select 学号=StuId,姓名=StuName From tblStudent st Where (Select Count(*) From (Select Distinct CourseId From tblScore Where StuId=st.StuId) as tmp)=1
28、查询男生、女生人数
Select 男生人数=(select Count(*) From tblStudent Where StuSex='男'), 女生人数=(select Count(*) From tblStudent Where StuSex='女')
29、查询姓“张”的学生名单
Select * From tblStudent Where StuName like '张%'
30、查询同名同性学生名单，并统计同名人数
Select Distinct 学生姓名=StuName,同名人数=(Select Count(*) From tblStudent s2 Where s2.StuName=st.StuName) From tblStudent st Where (Select Count(*) From tblStudent s2 Where s2.StuName=st.StuName)>=2
31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)
Select * From tblStudent Where Year(Sage)=1981
32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
Select 课程ID=CourseId,课程名称=CourseName,平均成绩=(Select Avg(Score) From tblScore Where CourseId=cs.CourseId) From tblCourse cs Order by 平均成绩,CourseId Desc
33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
Select 学号=StuId,姓名=StuName,平均成绩=(Select Avg(Score) From tblScore Where StuId=st.StuId) From tblStudent st Where (Select Avg(Score) From tblScore Where StuId=st.StuId)>85
34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数
Select 姓名=StuName,分数=Score From tblScore sc Inner Join tblStudent st On sc.StuId=st.StuId Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where CourseName='数据库' And Score<60
35、查询所有学生的选课情况；
Select 学号=StuId,选课数=(Select Count(*) From (Select Distinct CourseId From tblScore Where StuId=st.StuId) as tmp) From tblStudent st
Select distinct 姓名=StuName,选修课程=CourseName From tblScore sc Inner Join tblStudent st On sc.StuId=st.StuId Inner Join tblCourse cs On sc.CourseId=cs.CourseId
36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
Select 姓名=StuName,课程名称=CourseName,分数=Score From tblScore sc Inner Join tblStudent st On sc.StuId=st.StuId Inner Join tblCourse cs On sc.CourseId=cs.CourseId Where Score>=70
37、查询不及格的课程，并按课程号从大到小排列
Select * From tblScore Where Score<60 order by CourseId Desc
38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
Select StuId,StuName From tblStudent Where StuId in (Select StuId From tblScore Where CourseId='003' And Score>=80)
39、求选了课程的学生人数
Select 选了课程的学生人数=Count(*) From tblStudent st Where StuId IN (Select StuID From tblScore)
40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
Select CourseId,CourseName ,该科最高学生=(Select StuName From tblStudent Where StuId in (Select Top 1 StuID From tblScore Where CourseId=cs.CourseId Order by Score Desc)) ,成绩=(Select Top 1 Score From tblScore Where CourseId=cs.CourseId Order by Score Desc) From tblCourse cs Inner Join tblTeacher tc ON cs.TeaId=tc.TeaId Where TeaName='叶平'
41、查询各个课程及相应的选修人数
Select 课程ID=CourseId,选修人数=(Select Count(*) From (Select Distinct StuId From tblScore Where CourseId=cs.CourseId) as tmp) From tblCourse cs
42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
Select 学号=StuId, 课程号=CourseId, 成绩=Score From tblScore sc Where Exists (Select * From tblScore Where Score=sc.Score And StuId=sc.StuId And CourseId <>sc.CourseId) Order by 学号,成绩
43、查询每门功成绩最好的前两名
Select 课程号=CourseId, 第1名=(Select Top 1 StuId From tblScore Where CourseId=cs.CourseId Order by Score DESC), 第2名=(Select Top 1 StuID From (Select Top 2 StuId,Score From tblScore Where CourseId=cs.CourseId Order by Score DESC) as tmp Order by Score) From tblCourse cs
44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
Select 课程ID=CourseId,选修人数=(Select Count(*) From (Select Distinct StuId From tblScore Where CourseId=cs.CourseId) as tmp) From tblCourse cs Where (Select Count(*) From (Select Distinct StuId From tblScore Where CourseId=cs.CourseId) as tmp)>=10 Order by 选修人数 DESC, 课程ID
45、检索至少选修两门课程的学生学号
//没有重复课程数据时可用此方法
Select StuId from tblScore Group by Stuid having Count(*)>=2
//有重复课程时用此方法(如补考)：
Select StuId from tblStudent st Where (Select Count(*) From (Select Distinct CourseId From tblScore Where StuId=st.StuId) as tmp)>=2
46、查询全部学生都选修的课程的课程号和课程名
Select CourseId,CourseName From tblCourse cs Where Not Exists (Select * From tblStudent Where StuId Not In --没学过本课程的学生是否存在 (Select StuId From tblScore Where CourseId=cs.CourseId))
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
Select StuId,StuName From tblStudent Where StuId Not In ( Select StuID From tblScore sc Inner Join tblCourse cu ON sc.CourseId=cu.CourseId Inner Join tblTeacher tc ON cu.TeaId=tc.TeaId Where tc.TeaName='叶平' )
48、查询两门以上不及格课程的同学的学号及其平均成绩 Select StuID as 学号,Avg(Score) as 平均成绩 From tblScore sc Where (Select Count(*) From tblScore s1 Where s1.StuId=sc.StuId And Score<60)>=2 Group By StuId
49、检索“004”课程分数小于60，按分数降序排列的同学学号 (ok)
Select StuID,Score From tblScore Where CourseId='004' And Score<60 Order by Score Desc
50、删除“002”同学的“001”课程的成绩
Delete From SC Where StuId='1002' And CourseId='001'