// @nuget: EntityFramework

​

using System;

using System.Data.Entity;

using System.Linq;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations.Schema;

using System.ComponentModel.DataAnnotations;

​

public class Program

{

    public static void Main()

    {

        using (var context = new BookStore())

        {   

            BookCategory bc1 = new BookCategory()

            {

                BookId = 1,

                CategoryId = 1

            };

            BookCategory bc2 = new BookCategory()

            {

                BookId = 1,

                CategoryId = 2

            };

            BookCategory bc3 = new BookCategory()

            {

                BookId = 2,

                CategoryId = 1

            };

            BookCategory bc4 = new BookCategory()

            {

                BookId = 2,

                CategoryId = 2

            };

            Book book1 = new Book()

            {

                Title = "MyBook 1",

                BookCategories = new List<BookCategory>()

                {

                    bc1,

                    bc2

                }

            };

            Book book2 = new Book()

            {

                Title = "MyBook 2",

                BookCategories = new List<BookCategory>()

                {

                    bc3,

                    bc4

                }

            };

            Category category1 = new Category()

            {

                CategoryName = "category 1",

                BookCategories = new List<BookCategory>()

                {

                    bc1,

                    bc3

                }

            };

            Category category2= new Category()

            {

                CategoryName = "category 2",

                BookCategories = new List<BookCategory>()

                {

                    bc2,

                    bc4

                }

            };

            context.Books.Add(book1);

            context.Books.Add(book2);

            context.Categories.Add(category1);

            context.Categories.Add(category2);

​

            context.SaveChanges();

            var categories = context.Categories.ToList();

            var books = context.Books.ToList();

            var bookCategories = context.BookCategories.ToList();

            FiddleHelper.WriteTable(books);

            FiddleHelper.WriteTable(categories);

            FiddleHelper.WriteTable(bookCategories);

        }

    }

    public class BookStore : DbContext

    {

        public BookStore() : base(FiddleHelper.GetConnectionStringSqlServer())

        {

        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)

        {

        }

​

        public DbSet<Category> Categories { get; set; }

        public DbSet<Book> Books { get; set; }

        public DbSet<BookCategory> BookCategories { get; set; }

    }

​

    public class Book

    {

        public int BookId { get; set; }

        public string Title { get; set; }

        public virtual ICollection<BookCategory> BookCategories { get; set; }

    }

​

    public class Category

    {

        public int CategoryId { get; set; }

        public string CategoryName { get; set; }

        public virtual ICollection<BookCategory> BookCategories { get; set; }

    }

​

    public class BookCategory

    {

        [Key]

        public int BookId { get; set; }

        [Key]

        public int CategoryId { get; set; }

        public Book Book { get; set; }

        public Category Category { get; set; }

    }

}