sql server2012学习笔记

第1章 SQL安装

1-6 [SQL Server基础]什么是关系型数据库 (09:41)

简单记忆：一个table中的primary Keys是另一个Table中的Foreign Key

重点：：区分好主键和外键

第2章 T-SQL语句

2-1 [SQL Server基础]T-SQL简介 (06:38)

实际工作中少用*，因为可能会出现成千上万的数据

select Top 100 * from [Production].[Product]　　选择前一百行数据

select ProductID, Name, ProductNumber, Color, Size, ListPrice
from Production.Product

按信息读取数据

select ProductID, Name, ProductNumber, Color, Size, ListPrice
from Production.Product
order by listprice desc　　//安装listprice倒序排序

asc=ascending order　　//正序排序

第一个按照listprice倒序排序，第二个按照listprice和Name倒序排序

按照第2个Name正序排序

isnull(size,'') 空值null变换为单引号‘’里面的数据

改变列的名称

select ProductID, Name as ProductName, --using an alias
'The list price for ' + ProductNumber + ' is $ ' + convert(varchar,ListPrice) +'.' ,--using the concatenation to join character end-to-end.
'The list price for ' + ProductNumber + ' is $ ' + convert(varchar,ListPrice) +'.' as [Description] --using brackets to let SQL server conside the strin as a column name
from Production.Product

2-4 [SQL Server基础]where 关键字 (17:56)

在where语句中用>,=,<等字符

eg:

select * from [Sales].[SalesOrderHeader]
where SalesPersonID=275

select * from [Sales].[SalesOrderHeader]
where SalesOrderNumber='so43670'　　//string类型加单引号

where语句中使用or或and

eg:

select SalesOrderID,OrderDate,SalesPersonID,TotalDue as TotalSales
from [Sales].[SalesOrderHeader]
where SalesPersonID=275 and TotalDue>5000 and Orderdate between '2005-08-01' and '1/1/2006'

like中使用%号　　//%表示可以有，可以没有

select * from [Production].[Product]
where name like'Mountain'

select * from [Production].[Product]
where name like'%Mountain%' --Wildcard % matches any zero or more characters

_下划线表示前面有一个不知道的字符

select * from [Production].[Product]
where name like'_ountain%'

Where语句中使用in或not in

select * from [Production].[Product]
where color in ('red','white','black')

select * from [Production].[Product]
where class not in ('H') -- same as using: <> 'H'//没有H的

is null 与is not null

--Topic 10
select * from [Production].[Product]
where size is null

select * from [Production].[Product]
where size is not null

or与and的理解

--Topic 11
select * from [Production].[Product]
where color ='white'or color ='black'

select * from [Production].[Product]
where color ='white'and color ='black'

select SalesOrderID,OrderDate,SalesPersonID,TotalDue as TotalSales
from [Sales].[SalesOrderHeader]
where (SalesPersonID=275 or SalesPersonID=278) and TotalDue>5000

2-5 [SQL Server基础]聚合函数 (14:03)、

工作中常用的聚合函数&经典查询语句实例

select count(SalesPersonID)　　　　　//count--总和
from [Sales].[SalesOrderHeader]
where SalesPersonID is not null

select distinct(SalesPersonID)　　　　//l列出
from [Sales].[SalesOrderHeader]
where SalesPersonID is not null

select count(distinct(SalesPersonID))　　//数目
from [Sales].[SalesOrderHeader]
where SalesPersonID is not null

--Topic 13
select
Avg(TotalDue) as AverageTotalSales --aggregate functions
from [Sales].[SalesOrderHeader]

select
Avg(TotalDue) as AverageTotalSales
,Min(TotalDue) as MinimumTotalSales
,Max(TotalDue) as MaximumTotalSales
,Sum(TotalDue) as SummaryTotalSales
from [Sales].[SalesOrderHeader]

select SalesPersonID,OrderDate,Max(TotalDue) as MaximumTotalSales
from [Sales].[SalesOrderHeader]
where SalesPersonID is not null
group by SalesPersonID,OrderDate
having Max(TotalDue)>150000　　//大于15万的提取出来
order by SalesPersonID

----The classical T-SQL query!!!
select SalesPersonID,OrderDate,Max(TotalDue) as MaximumTotalSales
from [Sales].[SalesOrderHeader]
where SalesPersonID is not null and OrderDate >='2007/1/1'
group by SalesPersonID,OrderDate
having Max(TotalDue)>150000
order by SalesPersonID
--order by OrderDate desc

2-6 [SQL Server基础]两个技巧 (02:20)