SQL2005数据库笔记 二

                                                    SQL2005数据库笔记 二

--查询语句详细分析
--1.字段别名
字段名 as 别名***
字段名 别名
别名=字段名

select name,sex,city from student
select name as 姓名,性别=sex,city 城市 from student

select * from student

select name,birthday,city,sex from student

select name,year(getdate())-year(birthday) as 年龄,city,sex from student
 

--2.DISTINCT  : 针对纪录集，不是针对字段的 ，是查询记录集中不重复的记录

all   :所有信息记录
distinct :不重复的信息纪录

select * from student

select all * from student
select distinct * from student

select city,sex from student

select all city,sex from student

select distinct city,sex from student

select city from student

select distinct city from student

update student set city='广州' where city='34'

select distinct sex from student

select distinct class_type from student

--3.top
top n   前n条记录
top n percent 前n%条记录

select * from student

select top 3 * from student

select top 50 percent * from student

--4.between...and... 两者之间   数字
between...and... 在两者之间
not between...and... 不在两者之间
select * from student

alter table student add age as datepart(year,getdate())-year(birthday)

--age>=26
select * from student where age>=26
--age<=40
select * from student where age<=40

--age>=26    age<=40  [26,40]
select * from student where age>=26 and age<=40
select * from student where age between 26 and 40

--不在 [26,40]
select * from student where not (age>=26 and age<=40)
select * from student where age<26 or age>40

select * from student where not age between 26 and 40
select * from student where age not between 26 and 40

--5.in  
IN   在某个范围内
NOT IN  不在某个范围内
主要用于字符串,本身可以使用于任意类型

--北京
select * from student where city='北京'
--上海
select * from student where city='上海'

--北京  上海
select * from student where city='北京' or city='上海'

--北京  上海  香港
select * from student where city='北京' or city='上海' or city='香港'
select * from student where city in('北京','上海','香港')

--除北京  上海  香港
select * from student where not(city='北京' or city='上海' or city='香港')
select * from student where city!='北京' AND city!='上海' AND city!='香港'

select * from student where NOT city in('北京','上海','香港')
select * from student where city NOT in('北京','上海','香港')

select * from student

19 22 26

select * from student where age=19 or age=22 or age=26

select * from student where age in(19,22,26)

select * from student where birthday in('2000-1-1','2008-11-3')

print year(getdate())
print month(getdate())
print day(getdate())
--int
select name,sex from student

cast(year(birthday) as char(4))+'-'+
cast(month(birthday) as varchar(2))+'-'+
cast(day(birthday) as char(4))

--在将 varchar 值 'f' 转换成数据类型 int 时失败。

--类型转换函数 cast
cast(字段/变量 as 新类型)

--别名只是为了显示直观,功能有限制,
--只能在排序语法中直接使用,其他所有语法都不能使用

select name,birthday,cast(year(birthday) as char(4))+'-'+cast(month(birthday) as varchar(2))+'-'+cast(day(birthday) as char(4)) as birth,sex from student
where cast(year(birthday) as char(4))+'-'+cast(month(birthday) as varchar(2))+'-'+cast(day(birthday) as char(4)) in('2000-1-1','2008-11-3')

--查询统计今天过生日的学生信息
2008-11-6
--出生月份=当前日期月份
--出生日子=当前日期日子

select * from student
where month(birthday)=month(getdate())
and day(birthday)=day(getdate())

--6.查询中统配符的使用(模糊查询):(针对字符串)
%：代表任意多个字符，比如：“%S%”   类似windows *
_（下划线）：代表任意单个字符   类似windows ?

select * from student where name like '张%'

select * from student where name like '海%'

select * from student where name like '%海'

--包含 海
select * from student where name like '%海%'

select * from student where name like '_海%'

select * from student where name like '%海_'

select * from student where name like '海_'

select * from student where name like '_海'

 

--查询电话号码第一位是1的
select * from student where tele like '1%'
select * from student where tele like '2%'
select * from student where tele like '3%'
select * from student where tele like '4%'
--查询电话号码第一位是1 或2 或3 或4 的
select * from student
where tele like '1%' or tele like '2%' or tele like '3%' or tele like '4%'

--error:select * from student where tele in('1%','2%','3%','4%')

select * from student
where tele like '1%' or tele like '2%' or tele like '3%' or tele like '4%'

select * from student where tele like '[1234]%'
select * from student where tele like '[1,2,3,4]%'
select * from student where tele like '[1-4]%'

 

--不是1 2 3 4
select * from student
where not(tele like '1%' or tele like '2%' or tele like '3%' or tele like '4%')

select * from student
where tele not like '1%' and tele not like '2%' and tele not like '3%' and tele not like '4%'

 

select * from student where not tele like '[1234]%'

select * from student where tele not like '[1234]%'
select * from student where tele not like '[1,2,3,4]%'
select * from student where tele not like '[1-4]%'

select * from student where tele like '[^1234]%'
select * from student where tele like '[^1,2,3,4]%'
select * from student where tele like '[^1-4]%'

--张 王
select * from student where name like '[张王]%'

select * from student where name like '%[飞海]'

select * from student where class_type like '%[程]_'

--查询1980  1985  1990  1995出生的
select * from student
where cast(year(birthday) as char(4)) like '19[89][05]'

select * from student
where year(birthday) like '19[89][05]'

--查询2003  2004  2005入学的
select * from student
where stu_no like '200[3-5]%'

select * from student
where stu_no like '[2003,2004,2005]%'

 

--字符串函数
print substring('abcdef',2,3)
print substring('abcdef',2,30)+'dsdf'
print left('abcdef',3)
print right('abcdef',3)
print len('abc')
print len('abc   ') --len函数会自动去掉尾随空格
print lower('asdEdFDSd')
print upper('asdEdFDSd')

print replace('abcdefcdw','cd','1234')

print replace('abcdefcdw','cxd','1234')

select * from student where name like '张%'

select * from student where substring(name,1,1) = '张'

select * from student where left(name,1) = '张'

--统计全体学生有哪些姓
select left(name,1) as fname,name,city from student
select left(name,1) as ddd,name,city from student

update student set name='张'+name where name like '[0a]%'

select distinct left(name,1) as fname from student

 

000000000000000000000000000

--在查询的基础上创建表 表复制

select 字段列表 into 新表名 from 表名 where 条件

select * from student where city='北京'

select * into beijingTable from student where city='北京'

select * from beijingTable

select name,sex,city,class_type into t001  from student
where city='北京' and sex='男' and class_type='java开发工程师'

select * from t001

--表的备份

select * into student_bak from student

select * from student

 

delete from student_bak

--排序：  ORDER BY 字段名称 [ ASC 升序 | DESC 降序]

select * from student order by age
 
select * from student order by age asc

select * from student order by age desc

--top
select top 1 * from student order by age asc

select top 1 * from student order by age desc

select * from relation order by mark desc

select top 1 * from relation order by mark desc

select top 1 with ties * from relation order by mark desc

select top 3 with ties * from relation order by mark desc

select name,sex,city,class_type,age from student
order by sex desc,city asc,class_type asc,age asc

 

nan < nv

a~z  97~122

 

select name,sex,city,class_type,age from student
order by 2 desc,3 asc,4 asc,5 asc

select * from student order by age

select * from student order by 9

--查询语句中函数的使用： 聚合(统计)函数
--① avg、min、max、sum

select avg(age) from student

select
avg(age) as 平均年龄,
min(age) as 最小年龄,
max(age) as 最大年龄,
sum(age) as 年龄总和,
sum(fee) as 费用合计,
max(birthday) as 最大生日
from student

select
avg(age) as 平均年龄,
min(age) as 最小年龄,
max(age) as 最大年龄,
sum(age) as 年龄总和,
sum(fee) as 费用合计,
max(birthday) as 最大生日
from student where city='北京' and sex='男'

 

--② COUNT：
-- count(字段名称):只计算指定字段不为空(null)的个数
-- count(*)计算所有的行（包括有空值的行）

select * from student

update student set tele=null where id=1

select count(tele) as num from student

select count(city) as num from student

select count(distinct city) as num from student

--判断某个字段是否有重复值
select count(city) as num1,count(distinct city) as num2 from student

select count(stu_no) as num1,count(distinct stu_no) as num2 from student

delete from student where stu_no='200802008'
select count(stu_no) as num1,count(distinct stu_no) as num2 from relation

 

select avg(age) as avgage,count(*) as num from student

select count(*) as num from student where sex='男'

select count(*) as num from student where sex='男' and city='上海'

select
avg(age) as 平均年龄,
min(age) as 最小年龄,
max(age) as 最大年龄,
sum(age) as 年龄总和,
sum(fee) as 费用合计,
max(birthday) as 最大生日,count(*) as 人数
from student where city='北京' and sex='男'

 

--全体学生的平均年龄26
select avg(age) as avgage from student

--统计年龄大于26的学生信息
select * from student where age>26

--统计年龄大于全体学生的平均年龄的学生信息
select * from student
where age>(select avg(age) as avgage from student)

--子查询

--统计陈刚的总分
select sum(mark) as summark from relation
where stu_no=(select stu_no from student where name='陈刚')

--统计陈刚的总分和几门课
select sum(mark) as summark,count(*) as num from relation
where stu_no=(select stu_no from student where name='陈刚')

--统计陈刚的学号200507001
select stu_no from student where name='陈刚'

--统计200507001的总分
select sum(mark) as summark from relation where stu_no='200507001'

--统计200507001的relation信息
select * from relation where stu_no='200507001'

 

--统计平面设计课程的平均分和选修人数

select avg(mark) as avgmark,count(*) as num from relation
where c_no =(select c_no from course where c_name='平面设计')

 

--统计陈刚学习平面设计课程的成绩
select mark from relation
where stu_no=(select stu_no from student where name='陈刚')
and c_no=(select c_no from course where c_name='平面设计')

 

select mark from relation
where stu_no='200507001' and c_no='c_002'

陈刚的学号200507001
select stu_no from student where name='陈刚'
平面设计课程编号c_002
select c_no from course where c_name='平面设计'

 

--统计北京地区学生学习平面设计课程的人数
select count(*) as num from relation
where stu_no in(select stu_no from student where city='北京')
and c_no in (select c_no from course where c_name='平面设计')

 

select count(*) as num from relation
where stu_no in(select stu_no from student where city='北京')
and c_no=(select c_no from course where c_name='平面设计')

北京地区学生编号
200301001 200308002 200501011
select stu_no from student where city='北京'
平面设计课程编号c_002
select c_no from course where c_name='平面设计'

--统计200301001 200308002 200501011学习c_002课程的人数

select * from relation
where stu_no in('200301001', '200308002', '200501011')
and c_no in('c_002')

select * from student

--统计今天过生日的信息网络工程师学生学习平面设计课程的及格人数

select count(*) as num
from relation
where stu_no in(
select stu_no from student
where month(birthday)=month(getdate()) and day(birthday)=day(getdate()) and class_type='信息网络工程师')
and c_no in(select c_no from course where c_name='平面设计')
and mark>=60

 

今天过生日的信息网络工程师学生编号
select stu_no from student
where month(birthday)=month(getdate()) and day(birthday)=day(getdate()) and class_type='信息网络工程师'

平面设计课程编号
select c_no from course where c_name='平面设计'

 

--统计北京地区的年龄大于北京地区男生平均年龄的男生信息

select * from student
where city='北京' and sex='男'
and age>(select avg(age) as avgage from student where city='北京' and sex='男')

 

统计北京地区的男生信息
select * from student
where city='北京' and sex='男'
and age>(select avg(age) as avgage from student where city='北京' and sex='男')

 

北京地区男生平均年龄28

select avg(age) as avgage from student where city='北京' and sex='男'

--Sql环境中的常用日期函数：
 getdate()
 getutcdate()
 year()
 month()
 day()
 datepart()
 datename()
 dateadd()
 datediff()

--getdate()
格式:getdate()
功能:ff
返回值类型:datetime

print getdate()

select getdate()
select getdate() as currentDate,* from student

 

--getutcdate()
格式:getutcdate()
功能:返回表示当前的 UTC 时间（通用协调时间或格林尼治标准时间）
的 datetime 值。当前的 UTC 时间得自当前的本地时间和运行 Microsoft SQL Server 实例的计算机操作系统中的时区设置。
返回值类型:datetime

select getdate(),getutcdate()

--year month day   --int
select year(getdate()),month(getdate()),day(getdate())

 

--datepart()
格式: datepart(参数,日期)
功能:返回指定日期按照参数部分的返回值
返回值类型:int

print datepart(year,getdate())
print datepart(month,getdate())
print datepart(day,getdate())

print datepart(hour,getdate())
print datepart(minute,getdate())
print datepart(second,getdate())
print datepart(millisecond,getdate())

print datepart(year,getdate())+datepart(month,getdate())+datepart(day,getdate())

print 2008+11+8

print datepart(quarter,getdate())  --季度

print datepart(quarter,'2008-4-1')  --季度

print datepart(dayofyear,'2008-4-1')   

print datepart(dayofyear,getdate())   

print datepart(dayofyear,'2008-12-31')   
print datepart(dayofyear,'2007-12-31')   

print datepart(week,'2007-12-31')    --周

print datepart(week,getdate())    --周

print datepart(weekday,getdate())    --星期几

1 2 3 4 5 6 7
天一二 三四五六

 

---//
--datename()
格式: datename(参数,日期)
功能:返回指定日期按照参数部分的返回值
返回值类型:varchar

print datename(year,getdate())
print datename(month,getdate())
print datename(day,getdate())

print datename(hour,getdate())
print datename(minute,getdate())
print datename(second,getdate())
print datename(millisecond,getdate())

print datename(year,getdate())+datename(month,getdate())+datename(day,getdate())

print 2008+11+8

print datename(quarter,getdate())  --季度

print datename(quarter,'2008-4-1')  --季度

print datename(dayofyear,'2008-4-1')   

print datename(dayofyear,getdate())   

print datename(dayofyear,'2008-12-31')   
print datename(dayofyear,'2007-12-31')   

print datename(week,'2007-12-31')    --周

print datename(week,getdate())    --周

print datename(weekday,getdate())    --星期几

--dateadd()
格式:dateadd(参数,整数,日期)
功能:给指定日期按照参数增加整数个值
返回值类型:datetime

print dateadd(year,2,getdate())

select dateadd(year,2,getdate())
select dateadd(year,-2,getdate())

select dateadd(month,2,getdate())
select dateadd(month,-2,getdate())

select dateadd(day,2,getdate())
select dateadd(day,-2,getdate())

select dateadd(day,2,'2008-12-31')

select dateadd(hour,2,getdate())

--datediff()
格式:datediff(参数,开始日期,结束日期)
功能:返回结束日期按照参数减去开始日期的返回值
类型:int

print datediff(year,'1980-9-21',getdate())
print datediff(month,'1980-9-21',getdate())
print datediff(day,'1980-9-21',getdate())

print datediff(hour,'1980-9-21',getdate())
print datediff(minute,'1980-9-21',getdate())
print datediff(second,'1980-9-21',getdate())

print datediff(millisecond,'1980-9-21',getdate())

 

新

24小时  fabu

if datediff(hour,fabu,getdate())<=24 jfvfg

 

7天
if datediff(day,fabu,getdate())<=7 jfvfg

6)select year(getdate())-year(min(birthday)) as 最高年龄  from student
7)select datediff(yyyy,min(birthday),getdate()) as 最高年龄  from student
8)select max(datediff(yyyy,birthday,getdate())) as 最高年龄  from student

year yyyy/yy

00000000000000000000000000000

--查找表中某个字段的重复值

--判断student表中name字段是否有重复值，有输出

select name,count(*) as num from student group by name
having count(*)>1

select stu_no,count(*) as num from relation group by stu_no
having count(*)>1

select * from t001

insert into t001(name,sex,city,class_type) values('张星雨','男','dd','ddd')

delete from t001 where name in(
select name from t001 group by name
having count(*)>1
)

--多表连接查询
--1.交叉连接 Cross  join/,

create table test_table1
(
 name varchar(20),
 city varchar(20)
)
go
insert into test_table1(name,city) values('张三','北京')
insert into test_table1(name,city) values('李四','上海')
insert into test_table1(name,city) values('王明明','上海')
go
create table test_table2
(
 name varchar(20),
 sex  char(2),
 age  int
)
go
insert into test_table2(name,sex,age) values('张三','男',22)
insert into test_table2(name,sex,age) values('李倩','女',34)
insert into test_table2(name,sex,age) values('王明明','男',19)
go
select * from test_table1
select * from test_table2

select * from test_table1 cross join test_table2
select * from test_table1 , test_table2

--内连接
inner join... on 条件
,... where 条件

select * from test_table1 inner join test_table2
on test_table1.name=test_table2.name

select * from test_table1 , test_table2
where test_table1.name=test_table2.name

--/////////////

select test_table1.*,test_table2.sex,test_table2.age from test_table1 inner join test_table2
on test_table1.name=test_table2.name

select a.*,b.sex,b.age from test_table1 a inner join test_table2 b
on a.name=b.name

select * from test_table1 , test_table2
where test_table1.name=test_table2.name

select test_table1.*,test_table2.sex,test_table2.age from test_table1 , test_table2
where test_table1.name=test_table2.name

select a.*,b.sex,b.age from test_table1 a, test_table2 b
where a.name=b.name

 

select * from student
select * from relation

--name c_no  mark

select a.name,b.c_no,b.mark
from student a inner join relation b
on a.stu_no=b.stu_no

select a.name,b.c_no,b.mark
from student a , relation b
where a.stu_no=b.stu_no

select * from course
select * from relation

--stu_no  c_name  mark

select b.stu_no,a.c_name,b.mark
from course a inner join relation b
on a.c_no=b.c_no

select b.stu_no,a.c_name,b.mark
from course a , relation b
where a.c_no=b.c_no

select * from student
select * from course
select * from relation

--name c_name mark

select a.name,c.c_name,b.mark
from student a inner join relation b
on a.stu_no=b.stu_no inner join course c
on c.c_no=b.c_no

select a.name,b.c_name,c.mark
from student a,course b,relation c
where a.stu_no=c.stu_no and b.c_no=c.c_no

 

--姓名和总分(连接查询和分组查询综合)

--1.先连接再分组

select a.name,sum(b.mark) as summark from student a inner join  relation b
on a.stu_no=b.stu_no
group by a.name

--2.先分组再连接

select a.name,b.summark
from student a inner join
(select stu_no,sum(mark) as summark from relation group by stu_no) b
on a.stu_no=b.stu_no

 

drop table tempTable

--学号和总分
select stu_no,sum(mark) as summark from relation group by stu_no

select stu_no,sum(mark) as summark into tempTable from relation group by stu_no

select a.name,b.summark from student a inner join tempTable b
on a.stu_no=b.stu_no

 

--select * from course
--select * from (select * from (select * from course)b) a

 

--课程名称和平均分和选修人数(连接查询和分组查询综合)
--1.先连接再分组
select a.c_name,avg(b.mark) as avgmark,count(*) as num
from course a,relation b
where a.c_no=b.c_no
group by a.c_name

select a.c_name,avg(b.mark) as avgmark,count(*) as num
from course a inner join relation b
on a.c_no=b.c_no
group by a.c_name

--2.先分组再连接
select a.c_name,b.avgmark,b.num
from course a,
(select c_no,avg(mark) as avgmark,count(*) as num from relation group by c_no) b
where a.c_no=b.c_no

select a.c_name,b.avgmark,b.num
from course a inner join
(select c_no,avg(mark) as avgmark,count(*) as num from relation group by c_no) b
on a.c_no=b.c_no

--左连接
left outer join ... on 条件

select * from test_table1
select * from test_table2

select * from test_table1 a inner join test_table2 b on a.name=b.name

select * from test_table1 a left outer join test_table2 b on a.name=b.name

--右连接
right outer join ... on 条件

select * from test_table1 a right outer join test_table2 b on a.name=b.name

--完全连接
full outer join ... on 条件

select * from test_table1 a full outer join test_table2 b on a.name=b.name

 

--内连接  左连接  右连接

00000000000000000000000000000000000

 

 

--综合举例
--1.统计男女生选修平面设计课程的人数，结果显示性别和人数

select b.sex,count(*) as num from relation a,student b
where a.stu_no=b.stu_no and a.c_no in(select c_no from course where c_name='平面设计')
group by b.sex

--2.统计各个班别选修平面设计课程的人数，结果显示班别和人数

select b.class_type,count(*) as num from relation a,student b
where a.stu_no=b.stu_no and a.c_no in(select c_no from course where c_name='平面设计')
group by b.class_type

 

--3.统计各个姓选修平面设计课程的人数，结果显示姓和人数

select b.name like '_%',count(*) as num from relation a,student b
where a.stu_no=b.stu_no and a.c_no in(select c_no from course where c_name='平面设计')
group by b.name like '_%'

--4.统计各个城市选修平面设计课程的人数，结果显示城市和人数

select b.city,count(*) as num from relation a,student b
where a.stu_no=b.stu_no and a.c_no in(select c_no from course where c_name='平面设计')
group by b.city

00000000000000000000000000

--综合举例

--1.统计选修了c_002课程的学生编号
c_001
c_002
c_003
c_004

c_002
c_004

c_002

c_001
c_004

c_005
c_006

c_002
c_005
select stu_no from relation where c_no='c_002'

 --统计选修了c_002课程的学生基本信息
 select * from student
 where stu_no in(select stu_no from relation where c_no='c_002')
 --统计选修了c_002课程的学生姓名和总分
 --1.
 select a.name,sum(b.mark) as summark
 from student a,relation b where a.stu_no=b.stu_no
 and a.stu_no in(select stu_no from relation where c_no='c_002')
 group by a.name 
 --2.
 select a.name,b.summark
 from student a,
 (select stu_no,sum(mark) as summark from relation group by stu_no)b
 where a.stu_no=b.stu_no and a.stu_no in(select stu_no from relation where c_no='c_002')

 

 

 --姓名和总分
 --1.
 select a.name,sum(b.mark) as summark
 from student a,relation b where a.stu_no=b.stu_no
 group by a.name 
 --2.
 select a.name,b.summark
 from student a,
 (select stu_no,sum(mark) as summark from relation group by stu_no)b
 where a.stu_no=b.stu_no

 

 

--2.统计至少选修了c_002课程的学生编号1236(同1)
c_001
c_002
c_003
c_004

c_002
c_004

c_002

c_001
c_004

c_005
c_006

c_002
c_005
--3.统计只选修了c_002课程的学生编号
select stu_no from relation where c_no='c_002' 
intersect
select stu_no from relation group by stu_no having count(*)=1

或

select stu_no from relation where c_no='c_002' 
and stu_no in(select stu_no from relation group by stu_no having count(*)=1)

或

select stu_no from relation
where stu_no in(select stu_no from relation where c_no='c_002')
group by stu_no having count(*)=1

 

 

 --选修了c_002课程的学生编号
 select stu_no from relation where c_no='c_002' 
 --选修了1门课程的学生编号
 select stu_no from relation group by stu_no having count(*)=1

 

 select stu_no,count(*) as num from relation group by stu_no
 having count(*)=1

 --统计只选修了c_002课程的学生基本信息
 select * from student where stu_no in(
 select stu_no from relation where c_no='c_002' 
 intersect
 select stu_no from relation group by stu_no having count(*)=1
 )
 --统计只选修了c_002课程的学生姓名和总分
 
 --1.
 select a.name,sum(b.mark) as summark
 from student a,relation b where a.stu_no=b.stu_no
 and a.stu_no in(
  select stu_no from relation where c_no='c_002' 
  and stu_no in(select stu_no from relation group by stu_no having count(*)=1)
 )
 group by a.name 
 --2.
 select a.name,b.summark
 from student a,
 (select stu_no,sum(mark) as summark from relation group by stu_no)b
 where a.stu_no=b.stu_no and a.stu_no in(
  select stu_no from relation
  where stu_no in(select stu_no from relation where c_no='c_002')
  group by stu_no having count(*)=1

 )
--3.统计只选修了c_002课程的学生编号
--4.统计没有选修了c_002课程的学生编号
--5.统计选修了c_002以及c_004课程的学生编号
--6.统计至少选修了c_002以及c_004课程的学生编号
--7.统计只选修了c_002以及c_004课程的学生编号
--8.统计没有选修了c_002以及c_004课程的学生编号
--9.用一条ｓｑｌ语句统计各个城市的总人数以及姓张的人数
--10.用一条ｓｑｌ语句统计各门课程及格率
课程名称 选修总人数 及格人数 及格率
数据库  20   20   100%
网页设计 12   6   50%
C语言  0   0   没人选修
英语  8   0   0%
...
000000000000000000000000

--4.统计没有选修了c_002课程的学生编号
--select stu_no from relation where c_no!='c_002'
--
--select * from relation where c_no!='c_002'
select stu_no from relation
except
select stu_no from relation where c_no='c_002'

select distinct stu_no from relation where stu_no not in(
select stu_no from relation where c_no='c_002')

 --统计没有选修了c_002课程的学生基本信息
 select * from student where stu_no in(
  select distinct stu_no from relation where stu_no not in(
  select stu_no from relation where c_no='c_002') 
 )

 --统计没有选修了c_002课程的学生姓名和总分
 --1.
 select a.name,sum(b.mark) as summark from student a, relation b
 where a.stu_no=b.stu_no
 and a.stu_no in(
  select stu_no from relation
  except
  select stu_no from relation where c_no='c_002'
 )
 group by a.name

 --2.
 select a.name,b.summark
 from student a,
 (select stu_no,sum(mark) as summark from relation group by stu_no) b
 where a.stu_no=b.stu_no
 and a.stu_no in(
  select distinct stu_no from relation where stu_no not in(
  select stu_no from relation where c_no='c_002')
 )

 

--5.统计选修了c_002以及c_004课程的学生编号
/*error
--select stu_no from relation where c_no='c_002' and c_no='c_004'
--select stu_no from relation where c_no='c_002' or c_no='c_004'
--select stu_no from relation where c_no in('c_002','c_004')
*/

select stu_no from relation where c_no='c_002'
intersect
select stu_no from relation where c_no='c_004'

或

select stu_no from relation where c_no='c_002'
and stu_no in(select stu_no from relation where c_no='c_004')

--6.统计至少选修了c_002以及c_004课程的学生编号(同5)
--7.统计只选修了c_002以及c_004课程的学生编号
(select stu_no from relation where c_no='c_002'
intersect
select stu_no from relation where c_no='c_004'
)
intersect
select stu_no from relation  group by stu_no having count(*)=2

或

select stu_no from relation where c_no='c_002'
and stu_no in(select stu_no from relation where c_no='c_004')
and stu_no in(select stu_no from relation  group by stu_no having count(*)=2)

 

--选修了c_002以及c_004课程的学生编号
select stu_no from relation where c_no='c_002'
intersect
select stu_no from relation where c_no='c_004'

--选修了2门课的学生编号
select stu_no from relation  group by stu_no having count(*)=2

--select * from relation where stu_no in('200104010','200802005')

--8.统计没有选修了c_002以及c_004课程的学生编号
select stu_no from relation where stu_no not in(select stu_no from relation where c_no='c_002')
and stu_no in(
select stu_no from relation where stu_no not in(select stu_no from relation where c_no='c_004'))

--select * from relation where stu_no in('200507004')

--9.用一条ｓｑｌ语句统计各个城市的总人数以及姓张的人数

select a.city as 城市名称,a.num as 总人数,b.num as 姓张的人数
from
(select city,count(*) as num from student group by city)a ,
(select city,count(*) as num from student where name like '张%' group by all city)b
where a.city=b.city
    

--统计各个城市的总人数
select city,count(*) as num from student group by city
--姓张的人数
select city,count(*) as num from student where name like '张%' group by all city

 --用一条ｓｑｌ语句统计各个城市的总人数以及姓张的人数以及姓王的人数

select a.city as 城市名称,a.num as 总人数,b.num as 姓张的人数,c.num as 姓王的人数
from
(select city,count(*) as num from student group by city)a ,
(select city,count(*) as num from student where name like '张%' group by all city)b,
(select city,count(*) as num from student where name like '王%' group by all city)c
where a.city=b.city and a.city=c.city

 

--10.用一条ｓｑｌ语句统计各门课程及格率
课程名称 选修总人数 及格人数 及格率
数据库  20   20   100%
网页设计 12   6   50%
C语言  0   0   没人选修
英语  8   0   0%
...
00000000000000000000

--10.用一条ｓｑｌ语句统计各门课程及格率
课程名称 选修总人数 及格人数 及格率
数据库  20   20   100%
网页设计 12   6   50%
C语言  0   0   没人选修
英语  8   0   0%
...
select c.c_name as 课程名称,c.num as 选修总人数,d.num as 及格人数,
case c.num
 when 0 then '没人选修'
 else cast(round(cast(d.num as float)/cast(c.num as float)*100,2) as varchar(10))+'%'
end as 及格率
from
(
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation group by c_no) b
on a.c_no=b.c_no
)c,
(
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation where mark>=60 group by all c_no) b
on a.c_no=b.c_no
)d
where c.c_name=d.c_name

 

 

课程名称 选修总人数 及格人数
数据库  20   20   
网页设计 12   6   
C语言  0   0   
英语  8   0   

select c.c_name as 课程名称,c.num as 选修总人数,d.num as 及格人数
from
(
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation group by c_no) b
on a.c_no=b.c_no
)c,
(
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation where mark>=60 group by all c_no) b
on a.c_no=b.c_no
)d
where c.c_name=d.c_name

 

 

课程名称 选修总人数
数据库  20     
网页设计 12     
C语言  0      
英语  8      
--先分组再连接
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation group by c_no) b
on a.c_no=b.c_no

 

课程编号 选修总人数
c_001  20     
c_002  12     
c_003  0      
c_004  8      
select c_no,count(*) as num from relation group by c_no

select * from course

 

 

 

 

课程名称 及格人数
数据库  20   
网页设计 6   
C语言  0   
英语  0   
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation where mark>=60 group by all c_no) b
on a.c_no=b.c_no
00000000000000000000000000000

--null值替换函数:

isnull(字段/变量,替换的值)

如果字段或者变量为null值就换成新值,新值的类型必须和字段变量的类型一致

 

case 字段
when 值1 then 结果1
when 值2 then 结果2
...
else 结果n
end

select name,sex,city from student

select name,
case sex
 when '男' then 'boy'
 when '女' then 'girl'
end as sex
,city from student

select name,
case sex
 when '男' then 'boy'
 else 'girl'
end as sex
,city from student

int

print 5.0/2.0

print 2/5

print 2.0/5.0

real
float
numeric
decimal

cast(字段/变量 as 新类型)

print round(3.1415926,4)
00000000000000000000000000000

INSERT 语句进一步分析：
1)insert into 表名[（字段列表）] values(对应字段列表的结果) (单行插入)
2)insert into 表名 default values(单行插入)
3)insert into 表名 子查询语句(批量插入)

 

--1)insert into 表名[（字段列表）] values(对应字段列表的结果) (单行插入)

select * from course
insert into course(c_no,c_name,teacher) values('c_016','AAAA','王老师')

insert into course values('c_017','BBBB','赵老师')

--2)insert into 表名 default values(单行插入)
                     (默认值)

create table test
(
 id int identity,
 name varchar(20) default '无名',
 city varchar(20) default '没有写'
)

insert into test values('张三','北京')
insert into test values('李四','上海')

select * from test order by id asc

insert into test default values (只有在设置默认值的情况下该语法生效)

drop table test

--//
declare @n int
set @n=1
while (@n<=100000)
begin
 insert into test default values 
 set @n=@n+1
end

select * from test

3)insert into 表名 子查询语句(批量插入)

select * from test

delete from test

select * from test

insert into test select name,city from student

insert into test(name,city) select name,city from student

 

--删除没有参加考试的学生信息
delete from student where stu_no not in(select stu_no from relation)

--查询没有参加考试的学生信息
select * from student where stu_no not in(select stu_no from relation)

drop table 表名 : 物理删除表,完成后表结构也被删除了.
truncate table 表名 :清空表中的所有记录,效率高,不能添加where条件，是固定语法,完成表结构依然存在
delete from 表名:清空表中的所有记录,可以添加where条件,完成表结构依然存在

truncate table test

select * from test
000000000000000000000000000000

--视图创建语法
create  view 视图名称
[with  encryption ]  --加密
as
select语句

create  view 视图名称
as
select语句

--北京地区学生信息的视图

create view beijingView
as
select * from student where city='北京'

select * from beijingView

create view rateView
as
select c.c_name as 课程名称,c.num as 选修总人数,d.num as 及格人数,
case c.num
 when 0 then '没人选修'
 else cast(round(cast(d.num as float)/cast(c.num as float)*100,2) as varchar(10))+'%'
end as 及格率
from
(
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation group by c_no) b
on a.c_no=b.c_no
)c,
(
select a.c_name,isnull(b.num,0) as num
from course a left outer join
(select c_no,count(*) as num from relation where mark>=60 group by all c_no) b
on a.c_no=b.c_no
)d
where c.c_name=d.c_name

--//
select * from rateView
--//
select c.c_name as 课程名称,c.num as 选修总人数,d.num as 及格人数,case c.num  when 0 then '没人选修' else cast(round(cast(d.num as float)/cast(c.num as float)*100,2) as varchar(10))+'%' end as 及格率 from  ( select a.c_name,isnull(b.num,0) as num from course a left outer join  (select c_no,count(*) as num from relation group by c_no) b on a.c_no=b.c_no )c, ( select a.c_name,isnull(b.num,0) as num from course a left outer join  (select c_no,count(*) as num from relation where mark>=60 group by all c_no) b on a.c_no=b.c_no )d where c.c_name=d.c_name 

 

--修改alter
alter view beijingView
as
select id,name,sex,city,class_type from student where city='北京'

alter view beijingView(编号,姓名,性别,城市,班级类别)
as
select id,name,sex,city,class_type from student where city='北京'

alter view beijingView
as
select id 编号,name 姓名,sex 性别,city 城市,class_type 班级类别 from student where city='北京'

--//

alter view beijingView
with  encryption
as
select id 编号,name 姓名,sex 性别,city 城市,class_type 班级类别 from student where city='北京'

 

select * from beijingView

 

--删除视图语法
drop view 视图名称1,视图名称2,...

drop view rateView

select * from rateView

--直接简化查询语法

--间接简化查询语法
select * from  student
select * from  course
select * from  relation

create view fullView
as
select a.*,b.*,c.mark
from student a,course b,relation c
where a.stu_no=c.stu_no and b.c_no=c.c_no

select * from fullView

--姓名和总分
select name,sum(mark) as summark from fullView
group by name

--课程名称和平均分和选修人数
select c_name,avg(mark) as avgmark,count(*) as num from fullView
group by c_name

 

create table ssss
(
  id    int   identity
 city varchar(20) default '没有写',
    class_type    varchar(20),
    birthday    datetime
)

create table test
(
 id int identity,
 name varchar(20) default '无名',
 city varchar(20) default '没有写'
)

create table asdf1
(
     id   int identity,
 name varchar(20) default '无名',
 city varchar(20) default '没有写'
)

create table kkkk
(
   id   int identity,
   name  varchar(20)  default '无名'
   city  varchar(20) default '没有写'
)

drop table test

 

 

 

 

 

000000000000000000000000

 

CREATE  [UNIQUE]  [CLUSTERED  |  NONCLUSTERED]
INDEX  index_name
ON   table_name(column1)
[WITH  DROP_EXISTING]

--给学生表的city字段创建一个唯一性的聚集索引
create unique clustered index IX_student_city on student(city)

--给学生表的city字段创建一个唯一性的非聚集索引
create unique nonclustered index IX_student_city on student(city)

--给学生表的city字段创建一个非唯一性的非聚集索引
create nonclustered index IX_student_city on student(city)

 

truncate table ss

--删除
drop index 表名.索引名

drop index student.IX_student_city
00000000000000000000000000000000000000000000

-流程 控制:
-- BEGIN …END 程序块标识，类似于C语言的{  }
-- IF…ELSE 判断语句 
-- CASE…END 类似于C语言的switch( )语句
-- WHILE 循环语句

--1.条件结构
if (条件)
begin
 语句块1
end
else
begin
 语句块2
end

 

declare @n int
set @n=54
if (@n>0)
print '+++'
else
print 'not +++'

 

declare @n int
set @n=54
if (@n>0)
begin
print '正数'
print '+++'
end
else
begin
print '不是正数'
print 'not +++'
end

 

--判断学生表中是否存在姓张的
if exists(select * from student where left(name,1)='张')
print '存在'
else
print '不存在'

 

declare @count int
if exists(select * from student where left(name,1)='张')
begin
print '存在'
select @count=count(*) from student where left(name,1)='张'
print '有'+cast(@count as varchar(10))+'人'
end
else
print '不存在'

 

declare @count int
if exists(select * from student where left(name,1)='aa')
begin
print '存在'
select @count=count(*) from student where left(name,1)='aa'
print '有'+cast(@count as varchar(10))+'人'
end
else
print '不存在'

 

 

 

--2.选择结构
--case语法
一般用于查询语句select，基本语法格式有两种形式如下：
格式一:
case 字段
 when 结果1 then 改变后结果1
 when 结果2 then 改变后结果2
 ...
 when 结果n then 改变后结果n
 else  改变后结果n+1
end

格式二：
case
 when 表达式1 then 改变后结果1
 when 表达式2 then 改变后结果2
 ...
 when 表达式n then 改变后结果n
 else  改变后结果n+1
end

select name,sex,city from student

select name,
case sex
 when '男' then 'boy'
 when '女' then 'gril'
end as sex
,city from student

select name,
case sex
 when '男' then 'boy'
 else 'gril'
end as sex
,city from student

select name,
case
 when sex='男' then 'boy'
 when sex='女' then 'girl'
end as sex
,city from student

 

select * from student

<10000 低
>=10000  <15000 中
>=15000 高

select name,
case
 when fee<10000 then '低'
 when fee>=10000 and fee<15000 then '中'
 when fee>=15000 then '高'
end as pj
from student

 

select
case
 when fee<10000 then '低'
 when fee>=10000 and fee<15000 then '中'
 when fee>=15000 then '高'
end as pj,count(*) as num
from student
group by case
 when fee<10000 then '低'
 when fee>=10000 and fee<15000 then '中'
 when fee>=15000 then '高'
end

select * from relation

 

--mark
<60 不及格
>=60  <80 及格
>=80  <90 良好
>=90  <=100 优秀

统计各个等级的人数

select
case
 when mark<60 then  '不及格'
 when mark>=60 and mark<80 then  '及格'
 when mark>=80 and mark<90 then '良好'
 when mark>=90 and mark<=100 then '优秀'
end as pj,count(*) as num
from relation
group by case
 when mark<60 then  '不及格'
 when mark>=60 and mark<80 then  '及格'
 when mark>=80 and mark<90 then '良好'
 when mark>=90 and mark<=100 then '优秀'
end

--3.循环
while (条件)
begin
 循环代码
end

declare @n int
set @n=1
while (@n<=100)
begin
 print @n
 set @n=@n+1
end

--1+2+3+...+100
declare @n int
declare @sum int
set @sum=0
set @n=1
while (@n<=100)
begin
 set @sum=@sum+@n
 set @n=@n+1
end
print @sum

--1+3+5+...+99
declare @n int
declare @sum int
set @sum=0
set @n=1
while (@n<=100)
begin
 set @sum=@sum+@n
 set @n=@n+2
end
print @sum

--2+4+6+...+100
declare @n int
declare @sum int
set @sum=0
set @n=2
while (@n<=100)
begin
 set @sum=@sum+@n
 set @n=@n+2
end
print @sum

 

 

 

 

 

------------
--1+3+5+...+99   @sum1
--2+4+6+...+100  @sum2
--1+2+3+...+100
declare @n int
declare @sum1 int,@sum2 int
set @sum1=0
set @sum2=0
set @n=1
while (@n<=100)
begin
 if (@n % 2=1) set @sum1=@sum1+@n else set @sum2=@sum2+@n
 set @n=@n+1
end
print @sum1
print @sum2
print @sum1+@sum2

--if case while
过程和函数

 

补充：

--使用存储过程完成信息的添加 insert

select * from test

delete from test

insert into test
select top 3 name,sex,city from student order by age asc

--使用存储过程完成信息的添加 insert_test
create procedure insert_test
(
 @name varchar(50),
 @sex  char(2),
 @city  varchar(50)
)
as
begin
insert into test(name,sex,city) values(@name,@sex,@city)
if (@@rowcount=1)
print '添加成功'
else
print '添加失败'
end

print @@rowcount

select * from test

execute insert_test 'aa','bb','cc'

execute insert_test @name='张三',@city='武汉',@sex='男'

 

0000000000000000000000000000

 

--1.返回数值的用户自定义函数（标量函数）
语法格式：
create  function 函数名称
(
 参数1 类型,
 参数2 类型,
 ...
)
returns  data_type --代表函数返回值类型
[with  encryption]
as
begin
   function_body
   return  expression --函数返回值
end

--用户自定义函数可以接受零个或多个输入参数，
--函数的返回值可以是一个数值，也可以是一个表，
--用户自定义函数不支持输出参数

/*
f(n)=1+2+3+...+n
f(1)=1
f(2)=3
f(3)=6
...
*/

create function f(@n int)
returns int
as
begin
 declare @sum int
 declare @i int
 set @i=1
 set @sum=0
 while (@i< =@n )
 begin
  set @sum=@sum+@i
  set @i=@i+1
 end
 return @sum
end

 

--标量函数调用必须指定所有用户dbo
select dbo.f(100)
print dbo.f(100)

select dbo.f(10)
print dbo.f(10)

select dbo.f(100),* from student

--通过姓名获取总分
create function myfun001(@name varchar(20))
returns float
as
begin
 declare @sum float
 set @sum=0
 if exists(select * from student where name=@name )
 begin
  if exists(select * from relation where stu_no in(select stu_no from student where name=@name ))
  begin
   select @sum=sum(mark) from relation where stu_no in(select stu_no from student where name=@name )   
  end
  else
  begin 
   set @sum=-2
  end
 end
 else
 begin
  set @sum=-1
 end
 return @sum
end

--姓名不存在-1
--姓名存在但没有参加过考试-2
--存在总分

--select dbo.myfun001('张三')
declare @s float
set @s=dbo.myfun001('张三')
if (@s=-1)
print '查无此人'
else if (@s=-2)
print '张三没有参加过任何课程考试'
else
print '张三总分:'+cast(@s as varchar(20))

 

select name,round(dbo.myfun001(name),0) as zongfensex,city from student
order by 2 desc

--通过课程名称获取平均分

 

 

--2.内联（单语句）的返回表的用户自定义函数
语法如下：
create  function  function_name
(@parameter_name   data_type  [=default]
returns  table
[with  encryption]
as
return  (select_statement)

--city

create function myfun003(@city varchar(20))
returns table
as
return
select * from student where city=@city

select * from myfun002('北京')

select * from dbo.myfun002('北京')

 

--修改alter

alter function myfun002(@city varchar(20))
returns table
with  encryption
as
return
select name,sex,city,class_type from student where city=@city

--删除drop
drop function 函数名称1,函数名称2,...

drop function myfun002

 

00000000000000000000000000000

 

 

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