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Entity Framework 6.x - 创建模型来自于现有数据库

2024-07-16 17:16:46   219人阅读

 

Creating a Model from an Existing Database

一、创建数据库 Chapter2

USE masterGOCREATE DATABASE Chapter2GOUSE Chapter2GOCREATE TABLE [Meter]([MeterId] [int] NOT NULL IDENTITY(1, 1),[MeterName] [varchar] (30) COLLATE Chinese_PRC_CI_AS NOT NULL) ON [PRIMARY]GOALTER TABLE [Meter] ADD CONSTRAINT [PK_Meter] PRIMARY KEY CLUSTERED  ([MeterId]) ON [PRIMARY]GOCREATE 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]GOALTER TABLE [Poet] ADD CONSTRAINT [PK_Poet] PRIMARY KEY CLUSTERED  ([PoetId]) ON [PRIMARY]GOCREATE 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]GOALTER TABLE [Poem] ADD CONSTRAINT [PK_Poem] PRIMARY KEY CLUSTERED  ([PoemId]) ON [PRIMARY]GOALTER TABLE [Poem] ADD CONSTRAINT [FK_Poem_Meter] FOREIGN KEY ([MeterId]) REFERENCES [Meter] ([MeterId])GOALTER TABLE [Poem] ADD CONSTRAINT [FK_Poem_Poet] FOREIGN KEY ([PoetId]) REFERENCES [Poet] ([PoetId])GO
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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 Program10     {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。


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