SQL code/*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_scorefrom Student a , sc bwhere a.S# = b.S#group by a.S# , a.Snamehaving 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_scorefrom Student a , sc bwhere a.S# = b.S#group by a.S# , a.Snamehaving 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_scorefrom Student a left join sc bon a.S# = b.S#group by a.S# , a.Snamehaving 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1select count(Tname) ["李"姓老师的数量] from Teacher where Tname like N'李%'--方法2select 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1select 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2select 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3select 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1select 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2select 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) --11.2select 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.Snameorder 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 tset @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)》。