About EF and simple CRUD DEMO

First, the Entity Framework (Entity FrameWork) Introduction

　　• referred to as EF

　　• relations with Asp.Net MVC and ADO.NET relations

　　• ADO.NET Entity FrameWork is based on Microsoft's ADO.NET developed out of the corresponding object-relational (O / R Mapping) solution, is called early ObjectSpace, the latest version is EF6.0 [CodeOnly function have been better stand by】

　　• Entity Framework Entity FrameWork ADO.NET is a set of data to support the development of technology-oriented software applications. Microsoft is an ORM framework.

Second, what is the O / R Mapping

　　• The broad: ORM refers to the conversion between the object model and object-oriented relational database interface.

　　• In a narrow sense, ORM can be considered, based on the data stored in a relational database, data access interface a virtual object-oriented. Ideally, based on such an object-oriented interface, a OO persistent object should not need to know implementation details of any relational database storing data.

EF simple demonstration

The first step: Right-click -> Add New Item -> ADO.NET Entity Data Model

Step two: Entity Data Model Wizard, you can default

The third step: New Connection

 

The fourth step: the hook (that contains sensitive data in the connection string), the next step

 

Step Five: Select models include those database tables, can be completed

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace EFDemoFirst
 8 {
 9     class Program
10     {
11         static void Main(string[] args)
12         {
13             //添加一个添加操作
14             //1、声明一个EF的上下文
15             DEMOEntities dbContext = new DEMOEntities();
16             //2、声明一个实体
17             T_Seats seats = new T_Seats();
18             seats.userName = "test";
19             seats.pwdWord = "test1123";
20             //3、告诉EF做一个插入操作
21             dbContext.T_Seats.Add(seats);
22             //4、告诉上下文，把实体的变化保存到数据库里面去
23             dbContext.SaveChanges();
24             Console.Write("ok");
25             Console.ReadKey();
26         }
27     }
28 }

添加DEMO

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace EFDemoFirst
 8 {
 9     class Program
10     {
11         static void Main(string[] args)
12         {
13             //1、声明一个EF的上下文
14             DEMOEntities dbContext = new DEMOEntities();
15             //2、声明一个实体
16             T_Seats seats = new T_Seats();
17             seats.userName = "testTest";
18             seats.pwdWord = "123456 ";
19             seats.id = 4;
20             //3、告诉EF做更新操作
21             //System.Data.Entity.EntityState.Added:添加
22             //System.Data.Entity.EntityState.Deleted:删除
23             //System.Data.Entity.EntityState.Modified:修改
24             dbContext.Entry<T_Seats>(seats).State = System.Data.Entity.EntityState.Modified;
25             //4、告诉上下文，把实体的变化保存到数据库里面去
26             dbContext.SaveChanges(); //执行SQL脚本的地方
27             Console.Write("ok");
28             Console.ReadKey();
29         }
30     }
31 }

修改DEMO

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace EFDemoFirst
 8 {
 9     class Program
10     {
11         static void Main(string[] args)
12         {
13             //1、声明一个EF的上下文
14             DEMOEntities dbContext = new DEMOEntities();
15             ////2、声明一个实体
16             T_Seats seats = new T_Seats();
17             seats.id = 4; //删除的WHERE条件，不加全部删除
18             //3、告诉ef做更新操作
19             //system.data.entity.entitystate.added:添加
20             //system.data.entity.entitystate.deleted:删除
21             //system.data.entity.entitystate.modified:修改
22             dbContext.Entry<T_Seats>(seats).State = System.Data.Entity.EntityState.Deleted;
23             //4、告诉上下文，把实体的变化保存到数据库里面去
24             dbContext.SaveChanges(); //执行SQL脚本的地方
25             Console.Write("ok");
26             Console.ReadKey();
27         }
28     }
29 }

删除DEMO