一個項目SQL1

問題及描述：
--1.學生表
Student(S#,Sname,Sage,Ssex) --S# 學生編號,Sname 學生姓名,Sage 出生年月,Ssex 學生性別
--2.課程表
Course(C#,Cname,T#) --C# --課程編號,Cname 課程名稱,T# 教師編號
--3.教師表
Teacher(T#,Tname) --T# 教師編號,Tname 教師姓名
--4.成績表
SC(S#,C#,score) --S# 學生編號,C# 課程編號,score 分數
*/
--創建測試數據
create table Student(S# varchar(10),Sname nvarchar(10),Sage datetime,Ssex nvarchar(10))
insert into Student values('01' , N'趙雷' , '1990-01-01' , N'男')
insert into Student values('02' , N'錢電' , '1990-12-21' , N'男')
insert into Student values('03' , N'孫風' , '1990-05-20' , N'男')
insert into Student values('04' , N'李雲' , '1990-08-06' , N'男')
insert into Student values('05' , N'周梅' , '1991-12-01' , N'女')
insert into Student values('06' , N'吳蘭' , '1992-03-01' , N'女')
insert into Student values('07' , N'鄭竹' , '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'語文' , '02')
insert into Course values('02' , N'數學' , '01')
insert into Course values('03' , N'英語' , '03')
create table Teacher(T# varchar(10),Tname nvarchar(10))
insert into Teacher values('01' , N'張三')
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、查詢"01"課程比"02"課程成績高的學生的信息及課程分數
--1.1、查詢同時存在"01"課程和"02"課程的情況
select a.* , b.score [課程'01'的分數],c.score [課程'02'的分數] 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、查詢同時存在"01"課程和"02"課程的情況和存在"01"課程但可能不存在"02"課程的情況(不存在時顯示爲null)(以下存在相同內容時不再解釋)
select a.* , b.score [課程"01"的分數],c.score [課程"02"的分數] 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、查詢"01"課程比"02"課程成績低的學生的信息及課程分數
--2.1、查詢同時存在"01"課程和"02"課程的情況
select a.* , b.score [課程'01'的分數],c.score [課程'02'的分數] 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、查詢同時存在"01"課程和"02"課程的情況和不存在"01"課程但存在"02"課程的情況
select a.* , b.score [課程"01"的分數],c.score [課程"02"的分數] 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、查詢平均成績大於等於60分的同學的學生編號和學生姓名和平均成績
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、查詢平均成績小於60分的同學的學生編號和學生姓名和平均成績
--4.1、查詢在sc表存在成績的學生信息的SQL語句。
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、查詢在sc表中不存在成績的學生信息的SQL語句。
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、查詢所有同學的學生編號、學生姓名、選課總數、所有課程的總成績
--5.1、查詢所有有成績的SQL。
select a.S# [學生編號], a.Sname [學生姓名], count(b.C#) 選課總數, sum(score) [所有課程的總成績]
from Student a , SC b
where a.S# = b.S#
group by a.S#,a.Sname
order by a.S#
--5.2、查詢所有(包括有成績和無成績)的SQL。
select a.S# [學生編號], a.Sname [學生姓名], count(b.C#) 選課總數, sum(score) [所有課程的總成績]
from Student a left join SC b
on a.S# = b.S#
group by a.S#,a.Sname
order by a.S#

--6、查詢"李"姓老師的數量
--方法1
select count(Tname) ["李"姓老師的數量] from Teacher where Tname like N'李%'
--方法2
select count(Tname) ["李"姓老師的數量] from Teacher where left(Tname,1) = N'李'
/*
"李"姓老師的數量   
-----------
1
*/

--7、查詢學過"張三"老師授課的同學的信息
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'張三'
order by Student.S#

--8、查詢沒學過"張三"老師授課的同學的信息
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'張三') order by m.S#

--9、查詢學過編號爲"01"並且也學過編號爲"02"的課程的同學的信息
--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、查詢學過編號爲"01"但是沒有學過編號爲"02"的課程的同學的信息
--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、查詢沒有學全所有課程的同學的信息
--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、查詢至少有一門課與學號爲"01"的同學所學相同的同學的信息
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、查詢和"01"號的同學學習的課程完全相同的其他同學的信息
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、查詢沒學過"張三"老師講授的任一門課程的學生姓名
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'張三')
order by student.S#

--15、查詢兩門及其以上不及格課程的同學的學號，姓名及其平均成績
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、檢索"01"課程分數小於60，按分數降序排列的學生信息
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、按平均成績從高到低顯示所有學生的所有課程的成績以及平均成績
--17.1 SQL 2000 靜態
select a.S# 學生編號 , a.Sname 學生姓名 ,
       max(case c.Cname when N'語文' then b.score else null end) [語文],
       max(case c.Cname when N'數學' then b.score else null end) [數學],
       max(case c.Cname when N'英語' then b.score else null end) [英語],
       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 動態
declare @sql nvarchar(4000)
set @sql = 'select a.S# ' + N'學生編號' + ' , a.Sname ' + N'學生姓名'
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 有關sql 2005的動靜態寫法參見我的文章《普通行列轉換(version 2.0)》或《普通行列轉換(version 3.0)》。

--18、查詢各科成績最高分、最低分和平均分：以如下形式顯示：課程ID，課程name，最高分，最低分，平均分，及格率，中等率，優良率，優秀率
--及格爲>=60，中等爲：70-80，優良爲：80-90，優秀爲：>=90
--方法1
select m.C# [課程編號], m.Cname [課程名稱],
  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 < 80 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [中等率(%)],
  cast((select count(1) from SC where C# = m.C# and score >= 80 and score < 90 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [優良率(%)],
  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)) [優秀率(%)]
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# [課程編號], m.Cname [課程名稱],
  (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 < 80 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [中等率(%)],
  cast((select count(1) from SC where C# = m.C# and score >= 80 and score < 90 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [優良率(%)],
  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)) [優秀率(%)]
from Course m
order by m.C#

--19、按各科成績進行排序，並顯示排名
--19.1 sql 2000用子查詢完成
--Score重複時保留名次空缺
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重複時合併名次
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重複時保留名次空缺(rank完成)
select t.* , px = rank() over(partition by c# order by score desc) from sc t order by t.C# , px
--Score重複時合併名次(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、查詢學生的總成績並進行排名
--20.1 查詢學生的總成績
select m.S# [學生編號] ,
       m.Sname [學生姓名] ,
       isnull(sum(score),0) [總成績]
from Student m left join SC n on m.S# = n.S#
group by m.S# , m.Sname
order by [總成績] desc
--20.2 查詢學生的總成績並進行排名，sql 2000用子查詢完成，分總分重複時保留名次空缺和不保留名次空缺兩種。
select t1.* , px = (select count(1) from
(
  select m.S# [學生編號] ,
         m.Sname [學生姓名] ,
         isnull(sum(score),0) [總成績]
  from Student m left join SC n on m.S# = n.S#
  group by m.S# , m.Sname
) t2 where 總成績 > t1.總成績) + 1 from
(
  select m.S# [學生編號] ,
         m.Sname [學生姓名] ,
         isnull(sum(score),0) [總成績]
  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 總成績) from
(
  select m.S# [學生編號] ,
         m.Sname [學生姓名] ,
         isnull(sum(score),0) [總成績]
  from Student m left join SC n on m.S# = n.S#
  group by m.S# , m.Sname
) t2 where 總成績 >= t1.總成績) from
(
  select m.S# [學生編號] ,
         m.Sname [學生姓名] ,
         isnull(sum(score),0) [總成績]
  from Student m left join SC n on m.S# = n.S#
  group by m.S# , m.Sname
) t1
order by px
--20.3 查詢學生的總成績並進行排名，sql 2005用rank,DENSE_RANK完成，分總分重複時保留名次空缺和不保留名次空缺兩種。
select t.* , px = rank() over(order by [總成績] desc) from
(
  select m.S# [學生編號] ,
         m.Sname [學生姓名] ,
         isnull(sum(score),0) [總成績]
  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 [總成績] desc) from
(
  select m.S# [學生編號] ,
         m.Sname [學生姓名] ,
         isnull(sum(score),0) [總成績]
  from Student m left join SC n on m.S# = n.S#
  group by m.S# , m.Sname
) t
order by px

--21、查詢不同老師所教不同課程平均分從高到低顯示
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