主键与外键、子语句查询.unique.check

主键：须   唯一性，不能为空。

create table bumen

(

code int primary key,--主键：须唯一性，不为空，

 

--(表示设置主键)当code int primary key(1,2)时，表示code从1开始逐个加2,自增长，一般不用自增长列！

--设置主键可以 大 大 加快查询的速度。减缓插入的速度。

bumen varchar(20),

zhineng varchar(20),

ceo  varchar(20),

phone varchar(20),

)

Go

Drop table haha -–删除整个 haha表！

Create table haha

(

Code int ,

Name varchar(20),

Bumen  int references [dbo].[bumen]([code])           --  设置外键！外键约束：数据必须存在于‘主键’！

)

Go

直接操作时，下面操作！

在数据库 表中打开“设计”，右键单击创建列的左头端，打开~主键~设置‘主键’；

打开~关系~设置‘外键’。主键和外键要保证     数据类型一致    才可以设置关系！

use new

go

select *from haha 

------------从haha表查询部门人数大于等于5的最大年龄的人的信息！-------

-------------------子查询---------------------------------------------

select bumen ,COUNT(*)from haha  group by bumen having COUNT(*)>5

select MAX(age)from haha where bumen ='销售部'

select *from haha where bumen='销售部'and age =35

---------------------汇总查询-----------------------------------------

select *from haha where age =

(select MAX (age)from haha where bumen

in (select bumen  from haha group by bumen having COUNT (*)>=5))

and bumen=  (select bumen from haha  group by bumen

having COUNT(*)>=5)

----------------------按年龄升序排列，显示第6、7、8位的信息------------------

select top 8 *from haha order by age asc

select top 5 *from haha order by age asc

select top 3 *from haha where code  not in (select top 5 code from haha order by age )order by age

-----------------------------显示最大年龄、男性的信息--------------------

select top 1* from haha where sex='男' order by age desc

select *from haha where age=(select MAX(age)from haha where sex='男')and sex='男'

---------------------------------------------------------------------

select top 1 bumen ,COUNT (*)from haha group by bumen order by COUNT(*) desc

select distinct bumen from haha 

select *from haha where age=35 and bumen = '销售部'

select *from haha where age=35 and bumen =(select top 1 bumen from haha group by bumen order by COUNT(*)desc)

---------------------五个数据一组，     “分页”                      显示----------------

select  top 5 *from haha

select  top 5 *from haha where code not in(select top 5  code from haha )

select  top 5 *from haha where code not in(select top 10 code from haha )

--查看数据'分组的数量'（按每组5个分组，5.0表示浮点型数值，得出值也就是浮点型，取上限就可以了）----------------

select ceiling (COUNT(*)/5.0)from haha

------------------------------------------------新建bumen 表格-----------------------------------------

create table bumen

(

code int primary key,--主键：须唯一性，不为空，

--(表示设置主键)当code int primary key(1,2)时，表示code从1开始逐个加2,自增长，一般不用自增长列！

bumen varchar(20),

zhineng varchar(20),

ceo  varchar(20),

phone varchar(20),

)

go

insert into bumen values(1,'销售部','卖货','快结婚','1123456789')

insert into bumen values(2,'财务部','卖货','快结婚','2123456789')

insert into bumen values(3,'生产部','卖货','快结婚','3123456789')

insert into bumen values(4,'管理部','卖货','快结婚','4123456789')

go

select *from  bumen

select *from haha

select distinct bumen  from  haha

update haha set bumen=1 where bumen ='销售部'

update haha set bumen=2 where bumen ='财务部'

update haha set bumen=3 where bumen ='生产部'

update haha set bumen=4 where bumen ='管理部'

 --------------------------'利斯'所在部门的 信息-------------------------------------

select bumen from haha where name='利斯'

select *from bumen where bumen=(select bumen from haha where name='利斯')

----------------------------”快结婚“所在部门所有人的信息-----------------------------------------

select *from bumen where ceo='快结婚'

select * from haha where bumen =(select code from bumen where ceo='快结婚')order by code desc

###############  唯一性约束unique，check 约束  ###########################

类似于设置主键和外键，打开‘设计’在一行的左端右键单击，找到‘索引/键’，

--设置要选中‘列’--唯一性--

create table wtable

(

code int primary key,

name varchar(30),

cid  varchar(30)

)

go

create table atable

(

code int primary key,

name varchar(20),

cid varchar(50) unique--unique 代表唯一性！输入信息不能重复！

)

--create unique index_aaa --创建唯一性的索引‘aaa’ 作用在atable 中cid 列！

--on atable (cid) ----------这是在外部增加唯一性的表达方法！

insert into atable values (1,'呵呵','21432432432')

insert into atable values (2,'呵呵','21432432432')--此时这一条不能插入表中！cid信息重复。

select *from atable

([age]>(0)AND[age]<(150))--check 约束表达格式！