EF code first introduction and first instance

1. Introduction to EF code first

To be supplemented

 

Ii. EF code first simple instance

1. Development Environment and Database description

Development Environment: Visual Studio 2010 ultimate SP1 + SQL Server 2008 r2

Database: northwind

2. InstanceCodeStructure

Structure Description:

APP: Console ApplicationProgram

Data: Data Access

Domain: entity class

3. Install Entity Framework

In the Visual Studio Editor, choose tools> library Package Manager> Package Manager Console. In the Package Manager Console window, run the following statement to install the latest Entity Framework.

 
PM> install-package entityframework
 

The app layer and data layer Add references to the entityframework respectively:

 

After entityframework is installed on the app layer, the app. config and packages. config files are automatically added.

App. config configures the Entity Framework Version and database connection information, and modifies the data connection information to adapt to the local environment.

 1 <? XML version = "  1.0  " Encoding = "  UTF-8  " ?>
 2 <Configuration>
 3 <Configsections>
 4 <! -- For more information on Entity Framework configuration, visit http: // Go.microsoft.com/fwlink /? Linkid = 237468 -->  
  5 <Section name = "  Entityframework  " Type = "  System. Data. entity. Internal. configfile. entityframeworksection, entityframework, version = 4.3.1.0, culture = neutral, publickeytoken = b77a5c561934e089  " />
 6 </Configsections>
 7 <Entityframework>
8 <Defaconnecticonnectionfactory type = "  System. Data. entity. Infrastructure. sqlconnectionfactory, entityframework  " >
 9 <Parameters>
 10 <! -- <Parameter value = "  Data Source = (localdb) \ v11.0; Integrated Security = true; multipleactiveresultsets = true  " /> -->
 11 <Parameter value ="  Data Source = (local); User ID = sa; Password =; multipleactiveresultsets = true  " />
 12 </Parameters>
 13 </Defaultonfactory>
 14 </Entityframework>
 15 </Configuration>

Packages. config package used by the current project:

1<? XML version ="1.0"Encoding ="UTF-8"?>
2<Packages>
3<Package ID ="Entityframework"Version ="4.3.1"/>
4</Packages>
 

4. instance code

Category. CS in domain

 1   Using System;
2   Using System. Collections. Generic;
 3   Using System. LINQ;
 4   Using System. text;
 5  
 6   Namespace Northwind. domain. Entities
 7 {
 8       Public   Class Category
 9 {
 10           ///   <Summary>  
  11   ///  CATEGORY ID
  12   ///   </Summary>  
  13           Public   Int Categoryid {Get ; Set ;}
 14  
 15           ///   <Summary>  
  16   ///  Category name
  17   ///   </Summary>  
  18           Public  String Categoryname { Get ; Set ;}
 19 }
 20 }

Northwindcontext. CS in Data

 1   Using System;
 2   Using System. Collections. Generic;
 3   Using System. LINQ;
 4  Using System. text;
 5  
 6   Using System. Data. entity;
 7  
 8   Using Northwind. domain. entities;
 9  
 10   Namespace Northwind. Data
 11 {
 12      Public   Class Northwindcontext: dbcontext
 13 {
 14           Public Dbset <Category> categories { Get ; Set ;}
 15 }
 16 }

Program. CS in app

 1   Using System;
 2  Using System. Collections. Generic;
 3   Using System. LINQ;
 4   Using System. text;
 5  
 6   Using Northwind. Data;
 7   Using Northwind. domain. entities;
 8  
 9  Namespace Northwind. app
 10 {
 11       Class Program
 12 {
 13           Static   Void Main ( String [] ARGs)
 14 {
 15 Category C = New Category () {categoryname = "  Digital Electronics  " };
 16  
 17               Using (Northwindcontext DB = New Northwindcontext ())
 18 {
 19 DB. categories. Add (C );
 20 DB. savechanges ();
 21 }
 22  
 23 Console. writeline ( "  Finish  " );
 24 Console. readkey ();
 25 }
 26 }
 27 }

5. Running instructions

Since the above database connection string does not contain the specified database name, after the operation is successful, the following database and table will be created in the local data engine:

Database Name: northwind. Data. northwindcontext

Table Name: Categories

6. Sample Code attachment

Northwind.rar