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
create table Student(S# varchar(20),Sname varchar(10),Sage int,Ssex varchar(2))
前面加一列序号：
if
exists(select table_name from information_schema.tables
where table_name='Temp_Table')
drop table Temp_Table
go
select 排名=identity(int,1,1),* INTO Temp_Table from Student
go
select * from Temp_Table
go
drop database [ ] --删除空的没有名字的数据库
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；
select 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名到第名的学生成绩单：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,Course
where 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 Student group 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';
--------------------------------------------------------------------------------------------------------
学生表(学号、姓名、性别、年龄、所在系)
课程表(课程号、课程名、先修课号、学分)
学生选课表(学号、课程号、成绩)
--
1：查询全体学生的学号和姓名
--
2：查询全体学生的姓名、学号和所在系
--
3: 查询全体学生的详细记录
--
4: 查询全体学生的姓名及其出生年份
--
5：查询全体学生姓名、出生年份和所在系，要求用小写字母表示所有系名
--
6：查询选修了课程的学生学号
--
7：查询计算机系(IS)所有学生的名单
--
8：查询所有年龄在20以下学生的姓名和年龄
--
9: 查询考试成绩有不及格的学生的学号
--
10: 查询年龄在20-23 （包括20和23）之间的学生的姓名、系别和年龄
--
11: 查询信息系（IS）、数学系（MA）和计算机科学系（CS）学生的姓名和性别
--
12: 查询学号为95001的学生的详细情况
--
13: 查询所有姓林的学生的姓名、学号和性别
--
14: 查询姓“欧阳”且全名为三个汉字的学生的姓名
--
15：查询名字中第二个字为“燕”字的学生姓名和学号
--
16：查询所有不姓“刘”的学生的姓名
--
17：查询课程名为“DB_DESIGN”的课程号的学分
--
18：查询缺少成绩的学生的学号和相应的课程号（成绩字段值为Null）
--
19: 查询所有有成绩的学生的学号和课程号
--
20: 查询所有计算机系年龄在20以下的学生姓名
--
21: 查询选修了3号课程的学生的学号和成绩，查询结果按分数降序排列
--
22: 查询全体学生情况，查询结果按所在系的系号升序排列，同一系中的学生按年龄降序排列
--
23: 查询学生总人数
--
24: 查询选修了课程的学生人数
--
25: 计算1号课程的学生的平均成绩
--
26: 计算1号课程的学生的最高成绩分数
--
27：求各个课程号及相应的选课人数
--
28: 查询选修了三门以上课程的学生学号
--
29：查询每个学生及其选修课情况
--
30：查询每一门课的间接先行课
--
31：选修2号课程且成绩在90以上的学生的学号和姓名
--
32：查询每个学生的学号、姓名、选修的课程名及成绩
--
33：查询与’林燕芳’在同一个系学习的学生姓名
--
34: 查询其他系中比信息系某一学生小的学生姓名和年龄
--
35：查询所有选修了1号课程的学生的学生姓名
--
36：查询选修了全部课程的学生姓名
--
37：至少选修了学生95002选修全部课程的学生号码
1：
select Sno,Sname
from Student
2：
select Sno,Sname,Sdept
from Student
3：
select
*
from Student
/*
也可以逐一列出列名并用逗号分隔
*/
--
其中getdate是获取当前系统时间。这是一个获取到的结果 ：2008-12-11 16:02:17.967
--
datepart从获取到的系统时间中分离出需要的部分，这里是分离出年份，更多信息请查看SQL Server联机帮助
--
下面的 出生年 指定了别名来替代原来结果页出现的文字
4：
select Sname , (
datepart(
year,
getdate())
- Sage)
'
出生年
'
from Student
--
该实例利用了小写转换函数lower() 提示：通过查询分析器的 公用对象 的 字符串函数中你可以找到这个函数
5：
select Sname
'
姓名
' , (
datepart(
year,
getdate())
- Sage)
'
出生年
',
lower(Sdept)
'
所在系
'
from Student
6：
select Sno
from sc
--
这里将返回全部结果，有重复的值
select
distinct Sno
from sc
--
加入关键字distinct就可以去除重复结果，只留1个
--
sql 中默认对字符串大小写不敏感的，所以下面的sdept=’IS’你也可以写成sdept=’is’。如果你要启用大小写敏感，可以用下面的方法
if 敏感
select
*
from
table
where field1
="AAA" COLLATE Chinese_PRC_CS_AS
else
select
*
from
table
where field1
="AAA" COLLATE Chinese_PRC_CI_AS
COLLATE 的中文排序规则参数可用下列方式查到
SELECT
*
FROM ::fn_helpcollations()
where name
like
'
Chinese%
'
7:
select Sname
from student
where sdept
=
'
IS
'
8:
select Sname,Sage
from student
where Sage
<
20
9:
select Sno
from sc
where grade
<
60
--
如果要查询不在这个区间的记录，那只要改成 not between就可以了
10：
select Sname,Sdept,Sage
from student
where Sage
between
20
and
23
--
如果要查询不属于信息系、数学系和计算机科学系的，可以在in前面加上NOT
--
也可以这样子写：
select Sname,Ssex from student where Sdept='is' or sdept='ma' or sdept='cs'
11：
select Sname,Ssex
from student
where Sdept
in(
'
IS
',
'
MA
',
'
CS
')
--
或者是select * from student where sno = '95001'
12：
select
*
from student
where sno
like
'
95001
'：
--
like用于字符串匹配
--
百分号匹配多个字符，包括0个
13：
select Sname,Sno,Sage
from student
where sname
like
'
林%
'
--
一个下划线匹配单个字符
14：
select sname
from student
where sname
like
'
欧阳_
'
15：
select sname,sno
from student
where sname
like
'
_燕%
'
16：
select sname
from student
where sname
not
like
'
刘%
'
17：
select Ccredit
from course
where cname
like
'
DB\_DESIGN
'
escape
'
\
'
--
注意：这里不用使用 = null
18：
select sno,cno
from sc
where grade
is
null
19：
select sno,cno
from sc
where grade
is
not
null
20:
select sname
from student
where sdept
=
'
CS
'
and sage
<
20
21：
select sno,grade
from sc
where cno
=
3
order
by grade
desc
22：
select
*
from student
order
by sdept,sage
desc
23:：
select
count(
*)
from student
24：
select
count(
distinct sno)
from sc
25:
select
avg(grade)
from sc
where cno
=
'
1
'
26:
select
max(grade)
from sc
where cno
=
'
1
'
group
by 按照它后面的列值进行分组，相同的值被分在一组
27:
select cno,
count(sno)
from sc
group
by cno
--
having后面的条件是根据group by 分组后的结果再进行筛选，最后只给出满足条件的分组
--
where筛选的对象是整个表，而having则是分组
28:
select sno
from sc
group
by sno
having
count(sno)
>=
3
29：
select a.sname,b.cno
from student a ,sc b
where a.sno
=b.sno
或者
select a.sname,b.cno
from student a
left
outer
join sc b
on a.sno
=b.sno
where b.cno
is
not
null
--
自身连接
30：
select a.Cno,b.Cpno
from course a,course b
where a.Cpno
=b.Cno
--
31：
select student.sno,student.sname
from student,sc
where student.sno
=sc.sno
and
sc.cno
=
'
2
'
and
sc.grade
>=
90
--
32：
select student.sno,student.sname,course.cname,sc.grade
from (student
left
join sc
on student.sno
=sc.sno)
left
join course
on sc.cno
=course.cno
或者：
--
忽略cname和grade都为null的行
Select student.sno,sname,cname,grade
From student,sc,course
Where student.sno
=sc.sno
and sc.cno
=course.cno
--
33：
select sname
from student
where sdept
=(
select sdept
from student
where sname
=
'
林燕芳
')
--
34：
select sname,sage
from student
where sage
<any(
select sage
from student
where sdept
=
'
is
'
)
and sdept
<>
'
IS
'
--
35：利用 exists的查询
--
exists根据是否存在行返回true/false
--
如果要查询没有选修1号课程的学生姓名，只要使用NOT Exists即可
select
*
from student
where
exists(
select
1
from sc
where student.sno
=sc.sno
and cno
=
'
1
'
)
或者你可以使用连接查询
select
*
from student
left
join sc
on student.sno
=sc.sno
where sc.cno
=
'
1
'
--
36：
declare
@temp1
int
declare
@temp2
int
select
@temp1
=
count(
*)
from course
select
@temp2
=sno
from sc
group
by sno
having
count(sno)
=
@temp1
select sname
from student
where sno
in (
@temp2)
或者
--
就是转换成查询没有一门课程没有选修的学生姓名
--
如果把两个not都去掉就是查询所有有选修课程的学生
Select sname
from student
where
not
exists(
Select
1
from course
where
not
exists(
Select
1
from sc
where student.sno
=sc.sno
and course.cno
=sc.cno
)
)
--
37：
--
同样要进行转换：查询这样的学生，没有95002选修的课程而学生X没有选修的
Select
distinct sno
From sc scx
Where
not
exists
(
Select
1
from sc scy
Where scy.sno
=
'
95002
'
and
not
exists
(
Select
1
from sc scz
Where scz.sno
=scx.sno
and scz.cno
=scy.cno
)
)
and sno
!=
'
95002
'
插入语句：
1：对每一个系求平均年龄，并把结果存入数据库
需要创建一个表用来存储结果
Create
table Deptage
(
Sdept
char(
15),
Avgage
smallint
);
--
插入子查询结果
insert
into
Deptage(Sdept,Avgage)
select sdept,
avg(sage)
from student
group
by sdept
--
查看结果
select
*
from deptage
修改语句；
1：将学生95001的年龄改为22岁
Update student
Set sage
=
22
Where sno
=
'
95001
'
--
注意如果不带where，则修改全部记录
2：将所有的学生年龄加1岁(修改多个元组的值)
Update student
Set sage
=sage
+
1;
3：将计算机系全体同学的成绩置零（带子查询的修改语句）
Update sc
Set grade
=
0
Where
'
cs
'
=(
Select sdept
from student
Where student.sno
=sc.sno)
删除语句：
1：删除学号为95009的学生记录(删除后将无法回复)
Delete
from student
Where sno
=
'
95009
'
--
没有加where的话将删除该表全部记录
2：删除计算机科学系所有学生的选课记录
Delete
from sc
Where
'
cs
'
=(
Select sdept
From student
Where student.sno
=sc.sno
)
例1：查询至少选秀1号课程和3号课程号的学生号码。
答案
select a.学号
from sc a,sc b
where a.学号
=b.学号
and a.课程号
=
'
1
'
and b.课程号
=
'
3
'
例2：查询至少选修了一门直接先行课为5号课程的学生姓名。
答案：
select 姓名
from student
where 学号
in(
SELECT
[
学号
]
FROM
[
test
].
[
dbo
].
[
SC
]
where 课程号
in(
SELECT 课程号
from Course
where 先行课
=
'
5
'))
例子3：查询选修了全部课程的学生号码和姓名。
declare
@t1
int
declare
@t2
int
select
@t2
=
count(
*)
from Course
select
@t1
=学号
from SC
group
by 学号
having
count(学号)
=
@t2
--
print '@t1='+cast(@t1 as varchar)
Select 学号,姓名
from student
where 学号
=
@t1
例子4：查询信息系年龄最大的三个学生的学号及其年龄，结果按年龄降序排列。
select
top
3 学号,年龄
from Student
where 所在系
=
'
IS
'
order
by 年龄
desc
例子5：查询选修了2号课程的学生名字
select 姓名
from student
where 学号
in(
select 学号
from sc
where 课程号
=
2)
例子6：查询成绩为90分以上的学生名字和课程名字
select st.姓名,c.课程名
from student st
left
join sc s
on st.学号
=s.学号
left
join Course c
on s.课程号
=c.课程号
where st.学号
in (
select st.学号
from sc
where s.成绩
>=
90)
sql 取中间几条记录(
select
top 表达式)
--
查询从第M条至N条的记录，写到存储过程中就是输入参数
declare
@m
int
--
declare
@n
int
--
declare
@x
int
declare
@y
int
--
设置测试值
set
@m
=
3
set
@n
=
10
set
@x
=(
@n
-
@m
+
1)
set
@y
=(
@m
-
1)
/*
语法
Select top (n-(m-1)) * from [表名] where [parimary key] not in(select top (m-1)
[主键] from [表名] order by [排序字段及排序方法]) order by [排序字段及排序方法
];
*/
--
测试用例，因为T-sql top 后不支持表达式，故采取下面的方法
exec(
'
select top
'
+
@x
+
'
* from kf.T_Community where [C_ID] not in (select top
'
+
@y
+
'
[C_ID] from kf.T_Community order by [C_ID]) order by [C_ID]
')
--
PS：如果在Orcale中，可以直接通过rownumber来控制，这样就容易多了
