50个经典sql语句总结_50个经典sql语句
50个经典sql语句总结由刀豆文库小编整理，希望给你工作、学习、生活带来方便，猜你可能喜欢“50个经典sql语句”。
一个项目涉及到的50个Sql语句(整理版)--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
--
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))
--
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)
group by Student.S , Student.Sname , Student.Sage , Student.Ssex having count(C)
--
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 = 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
--
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)》。
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#1楼 得分：0回复于：2010-05-17 17:47:07 SQL code--
18、查询各科成绩最高分、最低分和平均分：以如下形式显示：课程ID，课程name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率--及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90--方法1 select m.C [课程编号], m.Cname [课程名称], max(n.score)[最高分],min(n.score)[最低分],cast(avg(n.score)as decimal(18,2))[平均分],cast((select count(1)from SC where C = m.C and score >= 60)*100.0 /(select count(1)from SC where C = m.C)as decimal(18,2))[及格率(%)],cast((select count(1)from SC where C = m.C and score >= 70 and score
cast((select count(1)from SC where C = m.C and score >= 80 and score
cast((select count(1)from SC where C = m.C and score >= 90)*100.0 /(select count(1)from SC where C = m.C)as decimal(18,2))[优秀率(%)] from Course m , SC n where m.C = n.C group by m.C , m.Cname order by m.C--方法2 select m.C [课程编号], m.Cname [课程名称]，(select max(score)from SC where C = m.C)[最高分],(select min(score)from SC where C = m.C)[最低分],(select cast(avg(score)as decimal(18,2))from SC where C = m.C)[平均分],cast((select count(1)from SC where C = m.C and score >= 60)*100.0 /(select count(1)from SC where C = m.C)as decimal(18,2))[及格率(%)],cast((select count(1)from SC where C = m.C and score >= 70 and score
cast((select count(1)from SC where C = m.C and score >= 80 and score
cast((select count(1)from SC where C = m.C and score >= 90)*100.0 /(select count(1)from SC where C = m.C)as decimal(18,2))[优秀率(%)] from Course m order by m.C
--
19、按各科成绩进行排序，并显示排名--19.1 sql 2000用子查询完成--Score重复时保留名次空缺
select t.* , px =(select count(1)from SC where C = t.C and score > t.score)+ 1 from sc t order by t.C , px
--Score重复时合并名次
select t.* , px =(select count(distinct score)from SC where C = t.C and score >= t.score)from sc t order by t.C , px
--19.2 sql 2005用rank,DENSE_RANK完成--Score重复时保留名次空缺(rank完成)select t.* , px = rank()over(partition by C order by score desc)from sc t order by t.C , px--Score重复时合并名次(DENSE_RANK完成)select t.* , px = DENSE_RANK()over(partition by C order by score desc)from sc t order by t.C , px
--20、查询学生的总成绩并进行排名--20.1 查询学生的总成绩 select m.S [学生编号] ，m.Sname [学生姓名] , isnull(sum(score),0)[总成绩] from Student m left join SC n on m.S = n.S group by m.S , m.Sname order by [总成绩] desc--20.2 查询学生的总成绩并进行排名，sql 2000用子查询完成，分总分重复时保留名次空缺和不保留名次空缺两种。
select t1.* , px =(select count(1)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(sum(score),0)[总成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t2 where 总成绩 > t1.总成绩)+ 1 from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(sum(score),0)[总成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t1 order by px
select t1.* , px =(select count(distinct 总成绩)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(sum(score),0)[总成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t2 where 总成绩 >= t1.总成绩)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(sum(score),0)[总成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t1 order by px--20.3 查询学生的总成绩并进行排名，sql 2005用rank,DENSE_RANK完成，分总分重复时保留名次空缺和不保留名次空缺两种。
select t.* , px = rank()over(order by [总成绩] desc)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(sum(score),0)[总成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t order by px
select t.* , px = DENSE_RANK()over(order by [总成绩] desc)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(sum(score),0)[总成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t order by px
--
21、查询不同老师所教不同课程平均分从高到低显示
select m.T , m.Tname , cast(avg(o.score)as decimal(18,2))avg_score from Teacher m , Course n , SC o where m.T = n.T and n.C = o.C group by m.T , m.Tname order by avg_score desc
--
22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩--22.1 sql 2000用子查询完成--Score重复时保留名次空缺
select * from(select t.* , px =(select count(1)from SC where C = t.C and score > t.score)+ 1 from sc t)m where px between 2 and 3 order by m.C , m.px--Score重复时合并名次
select * from(select t.* , px =(select count(distinct score)from SC where C = t.C and score >= t.score)from sc t)m where px between 2 and 3 order by m.C , m.px--22.2 sql 2005用rank,DENSE_RANK完成--Score重复时保留名次空缺(rank完成)select * from(select t.* , px = rank()over(partition by C order by score desc)from sc t)m where px between 2 and 3 order by m.C , m.px
--Score重复时合并名次(DENSE_RANK完成)select * from(select t.* , px = DENSE_RANK()over(partition by C order by score desc)from sc t)m where px between 2 and 3 order by m.C , m.px
--
23、统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比
--23.1 统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]--横向显示
select Course.C [课程编号] , Cname as [课程名称] ,sum(case when score >= 85 then 1 else 0 end)[85-100],sum(case when score >= 70 and score
sum(case when score >= 60 and score
sum(case when score
where SC.C = Course.C
group by Course.C , Course.Cname order by Course.C--纵向显示1(显示存在的分数段)select m.C [课程编号] , m.Cname [课程名称] , 分数段 =（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)，count(1)数量
from Course m , sc n where m.C = n.C
group by m.C , m.Cname ,（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)order by m.C , m.Cname , 分数段
--纵向显示2(显示存在的分数段，不存在的分数段用0显示)select m.C [课程编号] , m.Cname [课程名称] , 分数段 =（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)，count(1)数量
from Course m , sc n where m.C = n.C
group by all m.C , m.Cname ,（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)order by m.C , m.Cname , 分数段
--23.2 统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[
--横向显示
select m.C 课程编号, m.Cname 课程名称,(select count(1)from SC where C = m.C and score
cast((select count(1)from SC where C = m.C and score
(select count(1)from SC where C = m.C and score >= 60 and score
cast((select count(1)from SC where C = m.C and score >= 60 and score
(select count(1)from SC where C = m.C and score >= 70 and score
cast((select count(1)from SC where C = m.C and score >= 70 and score
(select count(1)from SC where C = m.C and score >= 85)[85-100],cast((select count(1)from SC where C = m.C and score >= 85)*100.0 /(select count(1)from SC where C = m.C)as decimal(18,2))[百分比(%)] from Course m order by m.C--纵向显示1(显示存在的分数段)select m.C [课程编号] , m.Cname [课程名称] , 分数段 =（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)，count(1)数量 ，cast(count(1)* 100.0 /(select count(1)from sc where C = m.C)as decimal(18,2))[百分比(%)] from Course m , sc n where m.C = n.C
group by m.C , m.Cname ,（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)order by m.C , m.Cname , 分数段
--纵向显示2(显示存在的分数段，不存在的分数段用0显示)select m.C [课程编号] , m.Cname [课程名称] , 分数段 =（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)，count(1)数量 ，cast(count(1)* 100.0 /(select count(1)from sc where C = m.C)as decimal(18,2))[百分比(%)] from Course m , sc n where m.C = n.C
group by all m.C , m.Cname ,（case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score
when n.score >= 60 and n.score
else '0-60'
end)order by m.C , m.Cname , 分数段
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#2楼 得分：0回复于：2010-05-17 17:47:22 SQL code--
24、查询学生平均成绩及其名次
--24.1 查询学生的平均成绩并进行排名，sql 2000用子查询完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。select t1.* , px =(select count(1)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(cast(avg(score)as decimal(18,2)),0)[平均成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t2 where 平均成绩 > t1.平均成绩)+ 1 from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(cast(avg(score)as decimal(18,2)),0)[平均成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t1 order by px
select t1.* , px =(select count(distinct 平均成绩)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(cast(avg(score)as decimal(18,2)),0)[平均成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t2 where 平均成绩 >= t1.平均成绩)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(cast(avg(score)as decimal(18,2)),0)[平均成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t1 order by px--24.2 查询学生的平均成绩并进行排名，sql 2005用rank,DENSE_RANK完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。
select t.* , px = rank()over(order by [平均成绩] desc)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(cast(avg(score)as decimal(18,2)),0)[平均成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t order by px
select t.* , px = DENSE_RANK()over(order by [平均成绩] desc)from（select m.S [学生编号] ，m.Sname [学生姓名] , isnull(cast(avg(score)as decimal(18,2)),0)[平均成绩]
from Student m left join SC n on m.S = n.S
group by m.S , m.Sname)t order by px
--
25、查询各科成绩前三名的记录--25.1 分数重复时保留名次空缺
select m.* , n.C , n.score from Student m, SC n where m.S = n.S and n.score in
(select top 3 score from sc where C = n.C order by score desc)order by n.C , n.score desc--25.2 分数重复时不保留名次空缺，合并名次--sql 2000用子查询实现
select * from(select t.* , px =(select count(distinct score)from SC where C = t.C and score >= t.score)from sc t)m where px between 1 and 3 order by m.C , m.px--sql 2005用DENSE_RANK实现
select * from(select t.* , px = DENSE_RANK()over(partition by C order by score desc)from sc t)m where px between 1 and 3 order by m.C , m.px
--
26、查询每门课程被选修的学生数
select C , count(S)[学生数] from sc group by C
--
27、查询出只有两门课程的全部学生的学号和姓名
select Student.S , Student.Sname from Student , SC
where Student.S = SC.S
group by Student.S , Student.Sname having count(SC.C)= 2 order by Student.S--
28、查询男生、女生人数
select count(Ssex)as 男生人数 from Student where Ssex = N'男' select count(Ssex)as 女生人数 from Student where Ssex = N'女' select sum(case when Ssex = N'男' then 1 else 0 end)[男生人数],sum(case when Ssex = N'女' then 1 else 0 end)[女生人数] from student select case when Ssex = N'男' then N'男生人数' else N'女生人数' end [男女情况] , count(1)[人数] from student group by case when Ssex = N'男' then N'男生人数' else N'女生人数' end
--
29、查询名字中含有“风”字的学生信息
select * from student where sname like N'%风%' select * from student where charindex(N'风' , sname)> 0
--30、查询同名同性学生名单，并统计同名人数
select Sname [学生姓名], count(*)[人数] from Student group by Sname having count(*)> 1
--
31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)select * from Student where year(sage)= 1990 select * from Student where datediff(yy,sage,'1990-01-01')= 0 select * from Student where datepart(yy,sage)= 1990 select * from Student where convert(varchar(4),sage,120)= '1990'
--
32、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列
select m.C , m.Cname , cast(avg(n.score)as decimal(18,2))avg_score from Course m, SC n where m.C = n.C
group by m.C , m.Cname
order by avg_score desc, m.C asc
--
33、查询平均成绩大于等于85的所有学生的学号、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))>= 85 order by a.S
--
34、查询课程名称为“数学”，且分数低于60的学生姓名和分数
select sname , score from Student , SC , Course
where SC.S = Student.S and SC.C = Course.C and Course.Cname = N'数学' and score
--
35、查询所有学生的课程及分数情况；
select Student.* , Course.Cname , SC.C , SC.score from Student, SC , Course
where Student.S = SC.S and SC.C = Course.C order by Student.S , SC.C
--
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 Student.* , Course.Cname , SC.C , SC.score
from Student, SC , Course
where Student.S = SC.S and SC.C = Course.C and SC.score >= 70 order by Student.S , SC.C
--
37、查询不及格的课程
select Student.* , Course.Cname , SC.C , SC.score
from Student, SC , Course
where Student.S = SC.S and SC.C = Course.C and SC.score
--
38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名；
select Student.* , Course.Cname , SC.C , SC.score
from Student, SC , Course
where Student.S = SC.S and SC.C = Course.C and SC.C = '01' and SC.score >= 80 order by Student.S , SC.C
--
39、求每门课程的学生人数
select Course.C , Course.Cname , count(*)[学生人数] from Course , SC
where Course.C = SC.C group by Course.C , Course.Cname order by Course.C , Course.Cname
--40、查询选修“张三”老师所授课程的学生中，成绩最高的学生信息及其成绩--40.1 当最高分只有一个时
select top 1 Student.* , Course.Cname , SC.C , SC.score
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 SC.score desc--40.2 当最高分出现多个时
select Student.* , Course.Cname , SC.C , SC.score
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' and SC.score =(select max(SC.score)from SC , Course , Teacher where SC.C = Course.C and Course.T = Teacher.T and Teacher.Tname = N'张三')--
41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
--方法1 select m.* from SC m ,(select C , score from SC group by C , score having count(1)> 1)n where m.C= n.C and m.score = n.score order by m.C , m.score , m.S--方法2 select m.* from SC m where exists(select 1 from(select C , score from SC group by C , score having count(1)> 1)n
where m.C= n.C and m.score = n.score)order by m.C , m.score , m.S
--
42、查询每门功成绩最好的前两名
select t.* from sc t where score in(select top 2 score from sc where C = T.C order by score desc)order by t.C , t.score desc
--
43、统计每门课程的学生选修人数（超过5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 Course.C , Course.Cname , count(*)[学生人数] from Course , SC
where Course.C = SC.C group by Course.C , Course.Cname having count(*)>= 5 order by [学生人数] desc , Course.C
--
44、检索至少选修两门课程的学生学号
select student.S , student.Sname from student , SC
where student.S = SC.S
group by student.S , student.Sname having count(1)>= 2 order by student.S
--
45、查询选修了全部课程的学生信息
--方法1 根据数量来完成select student.* from student where S in(select S from sc group by S having count(1)=(select count(1)from course))--方法2 使用双重否定来完成select t.* from student t where t.S not in（select distinct m.S from
（select S , C from student , course)m where not exists(select 1 from sc n where n.S = m.S and n.C = m.C))--方法3 使用双重否定来完成select t.* from student t where not exists(select 1 from（select distinct m.S from
（select S , C from student , course)m where not exists(select 1 from sc n where n.S = m.S and n.C = m.C))k where k.S = t.S)
--
46、查询各学生的年龄--46.1 只按照年份来算
select * , datediff(yy , sage , getdate())[年龄] from student--46.2 按照出生日期来算，当前月日
--
47、查询本周过生日的学生 select * from student where datediff(week,datename(yy,getdate())+ right(convert(varchar(10),sage,120),6),getdate())= 0
--
48、查询下周过生日的学生 select * from student where datediff(week,datename(yy,getdate())+ right(convert(varchar(10),sage,120),6),getdate())=-1
--
49、查询本月过生日的学生 select * from student where datediff(mm,datename(yy,getdate())+ right(convert(varchar(10),sage,120),6),getdate())= 0
--50、查询下月过生日的学生 select * from student where datediff(mm,datename(yy,getdate())+ right(convert(varchar(10),sage,120),6),getdate())=-1
drop table Student,Course,Teacher,SC
