Sql server 查询

--Student(S#,Sname,Sage,Ssex) 学生表

--Course(C#,Cname,T#) 课程表

--SC(S#,C#,score) 成绩表

--Teacher(T#,Tname) 教师表

--问题：

--1、查询""课程比""课程成绩高的所有学生的学号；

select
a.S#
from (select
s#,score
from
SC
where
C#='001')
a,(select
s#,score

from
SC
where
C#='002')
b

where
a.score>b.score and a.s#=b.s#;

--2、查询平均成绩大于分的同学的学号和平均成绩；

select
S#,avg(score)

from
sc

group
by
S#
having
avg(score)
>60;

--3、查询所有同学的学号、姓名、选课数、总成绩；

select
Student.S#,Student.Sname,count(SC.C#),sum(score)

from
Student
left
Outer
join
SC
on
Student.S#=SC.S#

group
by
Student.S#,Sname

--4、查询姓"李"的老师的个数；

select
count(distinct(Tname))

from
Teacher

where
Tname
like
'李%';

--5、查询没学过"叶平"老师课的同学的学号、姓名；

Student.S#,Student.Sname

from
Student

where
S#
not
in
(select
distinct(
SC.S#)
from SC,Course,Teacher
where
SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平');

--6、查询学过""并且也学过编号""课程的同学的学号、姓名；

select
Student.S#,Student.Sname
from
Student,SC
where
Student.S#=SC.S# and SC.C#='001'and
exists(
Select
*
from
SC
as
SC_2
where
SC_2.S#=SC.S# and SC_2.C#='002');

--7、查询学过"叶平"老师所教的所有课的同学的学号、姓名；

select
S#,Sname

from
Student

where
S#
in
(select
S#
from
SC ,Course ,Teacher
where
SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平'
group
by
S#
having
count(SC.C#)=(select
count(C#)
from

Course,Teacher
where
Teacher.T#=Course.T# and Tname='叶平'));

--8、查询课程编号""的成绩比课程编号""课程低的所有同学的学号、姓名；

Select
S#,Sname
from (select
Student.S#,Student.Sname,score ,(select
score
from
SC
SC_2
where
SC_2.S#=Student.S# and SC_2.C#='002')
score2

from
Student,SC
where
Student.S#=SC.S# and C#='001')
S_2
where
score2
<score;

--9、查询所有课程成绩小于分的同学的学号、姓名；

select
S#,Sname

from
Student

where
S#
not
in
(select
Student.S#
from
Student,SC
where
S.S#=SC.S# and score>60);

--10、查询没有学全所有课的同学的学号、姓名；

select
Student.S#,Student.Sname

from
Student,SC

where
Student.S#=SC.S#
group
by
Student.S#,Student.Sname
having
count(C#)
<(select
count(C#)
from Course);

--11、查询至少有一门课与学号为""的同学所学相同的同学的学号和姓名；

select
S#,Sname
from
Student,SC
where
Student.S#=SC.S# and C# in
select C#
from
SC
where
S#='1001';

--12、查询至少学过学号为""同学所有一门课的其他同学学号和姓名；

select
distinct
SC.S#,Sname

from
Student,SC

where
Student.S#=SC.S# and C# in
(select
C#
from
SC
where
S#='001');

--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；

update
SC
set
score=(select
avg(SC_2.score)

from
SC
SC_2

where
SC_2.C#=SC.C# )
from Course,Teacher
where
Course.C#=SC.C# and Course.T#=Teacher.T# and Teacher.Tname='叶平');

--14、查询和""号的同学学习的课程完全相同的其他同学学号和姓名；

select
S#
from
SC
where
C#
in
(select
C#
from
SC
where
S#='1002')

group
by

S#
having
count(*)=(select
count(*)
from
SC
where
S#='1002');

--15、删除学习"叶平"老师课的SC表记录；

Delect
SC

from
course
,Teacher

where
Course.C#=SC.C# and Course.T#= Teacher.T# and Tname='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""课程的同学学号、、

号课的平均成绩；

Insert
SC
select
S#,'002',(Select
avg(score)

from
SC
where
C#='002')
from
Student
where
S#
not
in
(Select
S#
from
SC
where
C#='002');

--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
S#
as
学生ID

,(SELECT
score
FROM
SC
WHERE
SC.S#=t.S# AND C#='004')
AS
数据库

,(SELECT
score
FROM
SC
WHERE
SC.S#=t.S# AND C#='001')
AS
企业管理

,(SELECT
score
FROM
SC
WHERE
SC.S#=t.S# AND C#='006')
AS
英语

,COUNT(*)
AS
有效课程数,
AVG(t.score)
AS
平均成绩

FROM
SC
AS
t

GROUP
BY
S#

ORDER
BY
avg(t.score)

--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
L.C#
As
课程ID,L.score
AS
最高分,R.score
AS
最低分

FROM
SC
L
,SC
AS
R

WHERE
L.C# = R.C# and

L.score =
(SELECT
MAX(IL.score)

FROM
SC
AS
IL,Student
AS
IM

WHERE
L.C# = IL.C# and IM.S#=IL.S#

GROUP
BY
IL.C#)

AND

R.Score

=
(SELECT
MIN(IR.score)

FROM
SC
AS
IR

WHERE
R.C# = IR.C#

GROUP
BY
IR.C#

);

--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

SELECT
t.C#
AS
课程号,max(course.Cname)AS
课程名,isnull(AVG(score),0)
AS
平均成绩

,100 *
SUM(CASE
WHEN
isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*)
AS
及格百分数

FROM
SC
T,Course

where
t.C#=course.C#

GROUP
BY
t.C#

ORDER
BY 100 *
SUM(CASE
WHEN
isnull(score,0)>=60 THEN 1 ELSE

0 END)/COUNT(*)
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（），马克思（），OO&UML （），数据库（）

SELECT
SUM(CASE
WHEN
C# ='001'
THEN
score
ELSE 0 END)/SUM(CASE
C#
WHEN
'001'
THEN 1 ELSE 0 END) AS
企业管理平均分

,100 *
SUM(CASE
WHEN
C# =
'001'
AND
score
>= 60 THEN 1 ELSE 0 END)/SUM(CASE
WHEN
C# =
'001'
THEN 1 ELSE 0 END

)
AS
企业管理及格百分数

,SUM(CASE
WHEN
C# =
'002'
THEN
score
ELSE 0 END)/SUM(CASE
C#
WHEN
'002'
THEN 1 ELSE 0 END) AS
马克思平均分

,100 *
SUM(CASE
WHEN
C# =
'002'
AND
score
>= 60 THEN 1 ELSE 0 END)/SUM(CASE
WHEN
C# =
'002'
THEN 1 ELSE 0 END) AS
马克思及格百分数

,SUM(CASE
WHEN
C# =
'003'
THEN
score
ELSE 0 END)/

SUM(CASE
C#
WHEN
'003'
THEN 1 ELSE 0 END) AS
UML平均分

,100 *
SUM(CASE
WHEN
C# =
'003'
AND
score
>= 60 THEN 1 ELSE 0 END)/SUM(CASE
WHEN
C# =
'003'
THEN 1 ELSE 0 END) AS
UML及格百分数

,SUM(CASE
WHEN
C# =
'004'
THEN
score
ELSE 0 END)/SUM(CASE
C#
WHEN
'004'
THEN 1 ELSE 0 END) AS
数据库平均分

,100

*
SUM(CASE
WHEN
C# =
'004'
AND
score
>= 60 THEN 1 ELSE 0 END)/SUM(CASE
WHEN
C# =
'004'
THEN 1 ELSE 0 END) AS
数据库及格百分数

FROM
SC

--21、查询不同老师所教不同课程平均分从高到低显示

SELECT
max(Z.T#)
AS
教师ID,MAX(Z.Tname)
AS
教师姓名,C.C#
AS
课程ＩＤ,MAX(C.Cname)
AS
课程名称,AVG(Score)
AS
平均成绩

FROM
SC
AS
T,Course
AS
C ,Teacher
AS
Z

where
T.C#=C.C# and C.T#=Z.T#

GROUP
BY
C.C#

ORDER
BY
AVG(Score)
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（），马克思（），UML （），数据库（）

[学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩

SELECT
DISTINCT
top 3

SC.S#
As
学生学号,

Student.Sname
AS
学生姓名
,

T1.score
AS
企业管理,

T2.score
AS
马克思,

T3.score
AS
UML,

T4.score
AS
数据库,

ISNULL(T1.score,0)
+
ISNULL(T2.score,0)
+
ISNULL(T3.score,0)
+
ISNULL(T4.score,0)
as
总分

FROM
Student,SC LEFT
JOIN SC
AS
T1

ON
SC.S# = T1.S# AND T1.C# =
'001'

LEFT
JOIN
SC
AS
T2

ON
SC.S# = T2.S# AND T2.C# =
'002'

LEFT
JOIN
SC
AS
T3

ON
SC.S# =T3.S# AND T3.C# =
'003'

LEFT
JOIN
SC
AS
T4

ON
SC.S# = T4.S# AND T4.C# =
'004'

WHERE
student.S#=SC.S# and

ISNULL(T1.score,0)
+
ISNULL(T2.score,0)
+
ISNULL(T3.score,0)
+
ISNULL(T4.score,0)

NOT
IN

(SELECT

DISTINCT

TOP 15 WITH
TIES

ISNULL(T1.score,0)
+
ISNULL(T2.score,0)
+
ISNULL(T3.score,0)
+
ISNULL(T4.score,0)

FROM
sc

LEFT
JOIN
sc
AS
T1

ON
sc.S# = T1.S# AND T1.C#=
'k1'

LEFT
JOIN
sc
AS
T2

ON
sc.S# = T2.S# AND T2.C# =
'k2'

LEFT
JOIN
sc
AS
T3

ON
sc.S# = T3.S# AND T3.C# =
'k3'

LEFT
JOIN
sc
AS
T4

ON
sc.S# = T4.S# AND T4.C# =
'k4'

ORDER
BY
ISNULL(T1.score,0)
+
ISNULL(T2.score,0)
+
ISNULL(T3.score,0)
+
ISNULL(T4.score,0)
DESC);

--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
SC.C#
as
课程ID, Cname as
课程名称

,SUM(CASE
WHEN
score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS
[100 - 85]

,SUM(CASE
WHEN
score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS
[85 - 70]

,SUM(CASE
WHEN
score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS
[70 - 60]

,SUM(CASE
WHEN
score < 60 THEN 1 ELSE 0 END) AS
[60 -]

FROM
SC,Coursewhere
SC.C#=Course.C#

GROUP
BY
SC.C#,Cname;

 

--24、查询学生平均成绩及其名次

SELECT 1+(SELECT
COUNT(
distinct
平均成绩)

FROM (SELECT
S#,AVG(score)
AS
平均成绩

FROM
SC

GROUP
BY
S#

)
AS
T1

WHERE
平均成绩
>
T2.平均成绩)
as
名次,

S#
as
学生学号,平均成绩

FROM (SELECT
S#,AVG(score)
平均成绩

FROM
SC

GROUP
BY
S#

)
AS
T2

ORDER
BY
平均成绩
desc;

 

--25、查询各科成绩前三名的记录:(不考虑成绩并列情况)

SELECT
t1.S#
as
学生ID,t1.C#
as
课程ID,Score
as
分数

FROM
SC
t1

WHERE
score
IN
(SELECT
TOP 3 score

FROM
SC

WHERE
t1.C#= C#
ORDER
BY
score
DESC

)

ORDER
BY
t1.C#;

--26、查询每门课程被选修的学生数

select
c#,count(S#)
from sc
group
by
C#;

--27、查询出只选修了一门课程的全部学生的学号和姓名

select
SC.S#,Student.Sname,count(C#)
AS
选课数

from
SC
,Student

where
SC.S#=Student.S#
group
by
SC.S# ,Student.Sname
having
count(C#)=1;

--28、查询男生、女生人数

Select
count(Ssex)
as
男生人数
from
Student
group
by
Ssex
having
Ssex='男';

Select
count(Ssex)
as
女生人数
from
Student
group
by
Ssex
having
Ssex='女'；

--29、查询姓"张"的学生名单

SELECT
Sname
FROM
Student
WHERE
Sname
like
'张%';

--30、查询同名同性学生名单，并统计同名人数

select
Sname,count(*)
from
Studentgroup
by
Sname
having count(*)>1;;

--31、年出生的学生名单(注：Student表中Sage列的类型是datetime)

select
Sname,
CONVERT(char (11),DATEPART(year,Sage))
as age

from
student

where
CONVERT(char(11),DATEPART(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
C#,Avg(score)
from SC
group
by
C#
order
by
Avg(score),C#
DESC ;

--33、查询平均成绩大于的所有学生的学号、姓名和平均成绩

select
Sname,SC.S# ,avg(score)

from
Student,SC

where
Student.S#=SC.S#
group
by
SC.S#,Sname
having
avg(score)>85;

--34、查询课程名称为"数据库"，且分数低于的学生姓名和分数

Select
Sname,isnull(score,0)

from
Student,SC,Course

where
SC.S#=Student.S# and SC.C#=Course.C#and
Course.Cname='数据库'and
score
<60;

--35、查询所有学生的选课情况；

SELECT
SC.S#,SC.C#,Sname,Cname

FROM
SC,Student,Course

where
SC.S#=Student.S# and SC.C#=Course.C# ;

--36、查询任何一门课程成绩在分以上的姓名、课程名称和分数；

SELECT
distinct
student.S#,student.Sname,SC.C#,SC.score

FROM
student,Sc

WHERE
SC.score>=70 AND SC.S#=student.S#;

--37、查询不及格的课程，并按课程号从大到小排列

select
c#
from
sc
where
scor
e
<60 order
by
C#
;

--38、查询课程编号为且课程成绩在分以上的学生的学号和姓名；

select
SC.S#,Student.Sname
from
SC,Student
where
SC.S#=Student.S# and Score>80 and C#='003';

--39、求选了课程的学生人数

select
count(*)
from
sc;

--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
Student.Sname,score

from
Student,SC,Course
C,Teacher

where
Student.S#=SC.S# and SC.C#=C.C# and

C.T#=Teacher.T# and Teacher.Tname='叶平'
and SC.score=(select
max(score)from
SC
where
C#=C.C# );

--41、查询各个课程及相应的选修人数

select
count(*)
from
sc
group
by
C#;

--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
distinct
A.S#,B.score
from
SC
A ,SC
B
where
A.Score=B.Score and A.C# <>B.C# ;

--43、查询每门功成绩最好的前两名

SELECT
t1.S#
as
学生ID,t1.C#
as
课程ID,Score
as
分数

FROM
SC
t1

WHERE
score
IN
(SELECT
TOP 2 score

FROM
SC

WHERE
t1.C#= C#

ORDER
BY
score
DESC

)

ORDER
BY
t1.C#;

--44、统计每门课程的学生选修人数（超过人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，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
C#
as
课程号,count(*)
as
人数

from
sc

group
by
C#

order
by
count(*)
desc,c#

--45、检索至少选修两门课程的学生学号

select
S#

from
sc

group
by
s#

having
count(*)
>
= 2

--46、查询全部学生都选修的课程的课程号和课程名

select
C#,Cname

from
Course

where
C#
in
(select
c#
from
sc
group
by
c#)

--47、查询没学过"叶平"老师讲授的任一门课程的学生姓名

select
Sname
from
Student
where
S#
not
in
(select
S#
from
Course,Teacher,SC
where
Course.T#=Teacher.T# and SC.C#=course.C# and Tname='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
S#,avg(isnull(score,0))
from SC
where
S# in
(select
S#
from
SC
where

score
<60 group
by
S#
having
count(*)>2)group
by
S#;

--49、检索""课程分数小于，按分数降序排列的同学学号

select
S#
from
SC
where
C#='004'and
score
<60 order
by
score
desc;

--50、删除""同学的""课程的成绩

delete
from
Sc
where
S#='001'and
C#='001';