Entity Framework 6.x - 创建模型来自于现有数据库

 

Creating a Model from an Existing Database

一、创建数据库 Chapter2

USE master
GO

CREATE DATABASE Chapter2
GO
USE Chapter2
GO

CREATE TABLE [Meter]
(
[MeterId] [int] NOT NULL IDENTITY(1, 1),
[MeterName] [varchar] (30) COLLATE Chinese_PRC_CI_AS NOT NULL
) ON [PRIMARY]
GO
ALTER TABLE [Meter] ADD CONSTRAINT [PK_Meter] PRIMARY KEY CLUSTERED  ([MeterId]) ON [PRIMARY]
GO

CREATE TABLE [Poet]
(
[PoetId] [int] NOT NULL IDENTITY(1, 1),
[FirstName] [varchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL,
[MiddleName] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL,
[LastName] [varchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL
) ON [PRIMARY]
GO
ALTER TABLE [Poet] ADD CONSTRAINT [PK_Poet] PRIMARY KEY CLUSTERED  ([PoetId]) ON [PRIMARY]
GO

CREATE TABLE [Poem]
(
[PoemId] [int] NOT NULL IDENTITY(1, 1),
[PoetId] [int] NOT NULL,
[Title] [varchar] (255) COLLATE Chinese_PRC_CI_AS NOT NULL,
[MeterId] [int] NOT NULL
) ON [PRIMARY]
GO
ALTER TABLE [Poem] ADD CONSTRAINT [PK_Poem] PRIMARY KEY CLUSTERED  ([PoemId]) ON [PRIMARY]
GO
ALTER TABLE [Poem] ADD CONSTRAINT [FK_Poem_Meter] FOREIGN KEY ([MeterId]) REFERENCES [Meter] ([MeterId])
GO
ALTER TABLE [Poem] ADD CONSTRAINT [FK_Poem_Poet] FOREIGN KEY ([PoetId]) REFERENCES [Poet] ([PoetId])
GO

View Code

二、创建项目 CreateModelFromExistingDatabase

三、更新 Entity Framework 到最新版本

四、添加模型文件

完成后，得到如下图模型视图：

重新编译一下项目。

下面我们利用上面建立的模型对数据库进行操作，代码如下：

 1 using System;  2 using System.Collections.Generic;  3 using System.Linq;  4 using System.Text;  5 using System.Threading.Tasks;  6  7 namespace CreateModelFromExistingDatabase  8 {  9 class Program 10  { 11 static void Main(string[] args) 12  { 13 //添加数据 14 using (var context = new Chapter2Entities()) 15  { 16 var poet = new Poet { FirstName = "John", LastName = "Milton" }; 17 var poem = new Poem { Title = "Paradise Lost" }; 18 var meter = new Meter { MeterName = "Iambic Pentameter" }; 19 poem.Meter = meter; 20 poem.Poet = poet; 21  context.Poems.Add(poem); 22 poem = new Poem { Title = "Paradise Regained" }; 23 poem.Meter = meter; 24 poem.Poet = poet; 25  context.Poems.Add(poem); 26 27 poet = new Poet { FirstName = "Lewis", LastName = "Carroll" }; 28 poem = new Poem { Title = "The Hunting of the Shark" }; 29 meter = new Meter { MeterName = "Anapestic Tetrameter" }; 30 poem.Meter = meter; 31 poem.Poet = poet; 32  context.Poems.Add(poem); 33 34 poet = new Poet { FirstName = "Lord", LastName = "Byron" }; 35 poem = new Poem { Title = "Don Juan" }; 36 poem.Meter = meter; 37 poem.Poet = poet; 38  context.Poems.Add(poem); 39 40  context.SaveChanges(); 41  } 42 //显示数据 43 using (var context = new Chapter2Entities()) 44  { 45 var poets = context.Poets; 46 foreach (var poet in poets) 47  { 48 Console.WriteLine("{0} {1}", poet.FirstName, poet.LastName); 49 foreach (var poem in poet.Poems) 50  { 51 Console.WriteLine("\t{0} ({1})", poem.Title, poem.Meter.MeterName); 52  } 53  } 54  } 55  Console.ReadKey(); 56  } 57  } 58 }

显示结果：

 在到数据库里看一下3个表情况。