E文好的可以直接看https://github.com/loresoft/EntityFramework.Extended
也可以在nuget上直接安装这个包
1、先更新VS的NuGet版本http://docs.nuget.org/docs/start-here/installing-nuget
2、修改默认地址：
Options => Package Manager => General
http://go.microsoft.com/fwlink/?LinkID=206669
3、安装包
To install EntityFramework.Extended, run the following command in the Package Manager Console
PM> Install-Package EntityFramework.Extended