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
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。