T-Sql（一）简单语法

　　Sql Server是鄙人学习的第一种数据库，对Sql Server有一种特别的情感，下面就说一下Sql Server的简单语法，适用初学者。

　　1,创建数据库create database

create database My_FrirstCreate           --创建数据库
go

use My_FrirstCreate           --连接数据库              
go

　　2,创建表create table

create table dbo.Students          --创建表（数据类型，是否NULL）
  (StudentID int primary key not null,
  Name varchar(25)not null,
  Scores int null)
go

　　3,插入数据insert

insert dbo.Students(StudentID,Name,Scores)    --插入数据    
   values(100204201,'张三',50)
go

insert dbo.Students
   values(100204202,'李四',null)
go

insert into table1              --利用insert，select向表里插数据      
select ID,Name,Date 
from table2
where Name="张三";
go

　　4,使用select，into创建新表

select{列名}       --使用select，into创建新表
into 新表名
from 旧表；

　　5,更新,删除数据update delete

update dbo.Students         --更新数据
   set Scores=70
   where StudentID=100204202
go
delete from Students
   where Name='张三'

　　6,改变字段的属性

alter table Produce.Product     --改变字段的属性
alter column Name char(50) not null

　　7,数据类型转换

print cast ('2011-12-12' as datetime)     --cast类型转换
print convert(datetime,getdate())         --convert类型转换

　　8,like查询语法

--检索名称以‘hl’开头的信息
select t.ProductKey,t.ModelName
from dbo.DimProduct t
where t.ModelName like 'hl%';
--检索名称以‘hl’结尾的信息
select t.ProductKey,t.ModelName
from dbo.DimProduct t
where t.ModelName like '%hl';
--检索名称类似‘hl’的信息
select t.ProductKey,t.ModelName
from dbo.DimProduct t
where t.ModelName like '%hl%';

　　9,条件查询语法

--每种颜色有多种件产品：
select COUNT(*) from dbo.DimProduct;
select * from dbo.DimProduct where Color = 'black';
select count(*) from dbo.DimProduct where Color = 'black';

--分组：
select color from dbo.DimProduct;
select color,COUNT(*) from dbo.DimProduct
group by Color;
--商品库中：相同颜色产品数量大于50的商品颜色
select color,COUNT(*) from dbo.DimProduct
group by Color
having count(*) >= 50;

select * from dbo.DimProduct
order by Color asc;

select color,COUNT(*) from dbo.DimProduct
group by Color
having count(*) >= 50
order by COUNT(*) asc;

select color,COUNT(*) from dbo.DimProduct
group by Color
having count(*) >= 50
order by COUNT(*) desc;

--商品库中：1998生产的，相同颜色产品数量大于5的商品颜色
select color,COUNT(*) from dbo.DimProduct
where YEAR(StartDate)=1998
group by Color
having count(*) >= 50
order by COUNT(*) desc;

select color,count(*) from dbo.DimProduct t
where YEAR(t.StartDate)>1998
group by color
having COUNT(*)>50
order by COUNT(*) desc;

　　10,联接join语法

select m.LoginID as ManagerLoginID,e.*       --左联接
from HumanResources.Employee e
left join HumanResources.Employee m
on m.employeeID = e.ManagerID

select m.LoginID as ManagerLoginID,e.*       --右联接
from HumanResources.Employee e
right join HumanResources.Employee m
on m.employeeID = e.ManagerID