// @nuget: EntityFramework

​

using System;

using System.Data.Entity;

using System.Linq;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations.Schema;

using System.ComponentModel.DataAnnotations;

using System.Data.Entity.Infrastructure;

​

public class Program

{

    public static void Main()

    {

        InsertData();

        Author existingAuthor;

        using(var context = new BookStore())

        {

            existingAuthor = context.Authors.FirstOrDefault();

        }

        using(var context = new BookStore())

        {       

            context.Entry(existingAuthor).State = EntityState.Unchanged;

            Console.WriteLine("Entity State: {0}", context.Entry(existingAuthor).State);

            context.SaveChanges();

        }

    }

    private static void DisplayTrackedEntities(DbChangeTracker changeTracker)

    {

        var entries = changeTracker.Entries();

        foreach (var entry in entries)

        {

            Console.WriteLine("Entity Name: {0}", entry.Entity.GetType().FullName);

            Console.WriteLine("Status: {0}", entry.State);

        }

    }

​

    public static void InsertData()

    {

        using (var context = new BookStore())

        {

            Author author1 = new Author()

            {

                Name = "Mark",

                Books = new List<Book>

                {

                    new Book() { Title = "Fundamentals of Computer Programming with C#"},

                    new Book() { Title = "Java: A Beginner's Guide"},

                }

            };

            Author author2 = new Author()

            {

                Name = "Andy",

                Books = new List<Book>

                {

                    new Book() { Title = "SQL: The Ultimate Beginners Guide"}

                }

            };

            Author author3 = new Author()

            {

                Name = "Johny",

                Books = new List<Book>

                {

                    new Book() { Title = "Learn VB.NET"},

                    new Book() { Title = "C# Fundamentals for Absolute Beginners"},

                }

            };

            context.Authors.Add(author1);

            context.Authors.Add(author2);

            context.Authors.Add(author3);

​

            context.SaveChanges();

        }

    }

    public class BookStore : DbContext

    {

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

        {

        }

​

        public DbSet<Author> Authors { get; set; }

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

    }

​

     public class Book

    {

        public int BookId { get; set; }

        public string Title { get; set; }

        public int AuthorId { get; set; }

        [ForeignKey("AuthorId")]

        public Author Author { get; set; }

    }

​

    public class Author

    {

        public int AuthorId { get; set; }

        public string Name { get; set; }

        public virtual ICollection<Book> Books { get; set; }

    }

}