1. 创建数据库表
CREATE TABLE [Album] ( [AlbumId] [int] NOT NULL IDENTITY(1, 1), [AlbumName] [varchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL ) ON [PRIMARY] GO ALTER TABLE [Album] ADD CONSTRAINT [PK_Album] PRIMARY KEY CLUSTERED ([AlbumId]) ON [PRIMARY] GO CREATE TABLE [Artist] ( [ArtistId] [int] NOT NULL IDENTITY(1, 1), [FirstName] [varchar] (50) COLLATE Chinese_PRC_CI_AS 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 [Artist] ADD CONSTRAINT [PK_Artist] PRIMARY KEY CLUSTERED ([ArtistId]) ON [PRIMARY] GO CREATE TABLE [LinkTable] ( [ArtistId] [int] NOT NULL, [AlbumId] [int] NOT NULL ) ON [PRIMARY] GO ALTER TABLE [LinkTable] ADD CONSTRAINT [PK_LinkTable] PRIMARY KEY CLUSTERED ([ArtistId], [AlbumId]) ON [PRIMARY] GO ALTER TABLE [LinkTable] ADD CONSTRAINT [FK_LinkTable_Album] FOREIGN KEY ([AlbumId]) REFERENCES [Album] ([AlbumId]) GO ALTER TABLE [LinkTable] ADD CONSTRAINT [FK_LinkTable_Artist] FOREIGN KEY ([ArtistId]) REFERENCES [Artist] ([ArtistId]) GO
表关系图：
2. 创建实体模型，如图
备注：明明选了3个表，为什么只有2个实体呢？
因为中间那个表为连接表，所以在映射实体的时候只有2个实体，这种情况叫 no payload 。
为什么连接表不会被创建成一个实体呢？
因为他没有自己的主键，如果给链接表加一个主键，那么创建的实体模型就会和数据库表关系一样，一个一个的对应上。
3. 操作实体类
1 using System; 2 3 namespace ConsoleApplication3 4 { 5 class Program 6 { 7 static void Main(string[] args) 8 { 9 //Insert 10 using (var context = new test2Entities()) 11 { 12 //添加一个艺术家属于2个专辑 13 var artist = new Artist { FirstName = "Alan", LastName = "Jackson" }; 14 var album1 = new Album { AlbumName = "Drive" }; 15 var album2 = new Album { AlbumName = "Live at Texas Stadium" }; 16 artist.Albums.Add(album1); 17 artist.Albums.Add(album2); 18 context.Artists.Add(artist); 19 20 //添加一个专辑有2个艺术家 21 var artist1 = new Artist { FirstName = "Tobby", LastName = "Keith" }; 22 var artist2 = new Artist { FirstName = "Merle", LastName = "Haggard" }; 23 var album = new Album { AlbumName = "Honkytonk University" }; 24 artist1.Albums.Add(album); 25 artist2.Albums.Add(album); 26 context.Albums.Add(album); 27 28 context.SaveChanges(); 29 } 30 31 //Select 32 using (var context = new test2Entities()) 33 { 34 Console.WriteLine("艺术家和他们的专辑..."); 35 var artists = context.Artists; 36 foreach (var artist in artists) 37 { 38 Console.WriteLine("{0} {1}", artist.FirstName, artist.LastName); 39 foreach (var album in artist.Albums) 40 { 41 Console.WriteLine("\t{0}", album.AlbumName); 42 } 43 } 44 45 Console.WriteLine("\n专辑中的艺术家..."); 46 var albums = context.Albums; 47 foreach (var album in albums) 48 { 49 Console.WriteLine("{0}", album.AlbumName); 50 foreach (var artist in album.Artists) 51 { 52 Console.WriteLine("\t{0} {1}", artist.FirstName, artist.LastName); 53 } 54 } 55 } 56 Console.ReadKey(); 57 } 58 } 59 }
输出：
程序运行3次后的数据库表结果：
Entity Framework 6.x 学习之 - 创建带连接表的实体模型 with Database First,布布扣,bubuko.com