static void Main(string[] args)

{

    using (var ctx = new SchoolDBEntities())

    {

        Console.WriteLine("Find Student");

        var std1 = ctx.Students.Find();

　　　　　//ctx.ChangeTracker.Enties()方法获取所有追踪实体的DbEntityEntry对象

        Console.WriteLine("Context tracking changes of {0} entity.", ctx.ChangeTracker.Entries().Count());

        DisplayTrackedEntities(ctx.ChangeTracker);

        Console.WriteLine("Find Standard");

        var standard = ctx.Standards.Find();

        Console.WriteLine("Context tracking changes of {0} entities.", ctx.ChangeTracker.Entries().Count());

        Console.WriteLine("");

        Console.WriteLine("Editing Standard");

        standard.StandardName = "Edited name";

        DisplayTrackedEntities(ctx.ChangeTracker);

        Teacher tchr = new Teacher() { TeacherName = "new teacher" };

        Console.WriteLine("Adding New Teacher");

        ctx.Teachers.Add(tchr);

        Console.WriteLine("");

        Console.WriteLine("Context tracking changes of {0} entities.", ctx.ChangeTracker.Entries().Count());

        DisplayTrackedEntities(ctx.ChangeTracker);

        Console.WriteLine("Remove Student");

        Console.WriteLine("");

        ctx.Students.Remove(std1);

        DisplayTrackedEntities(ctx.ChangeTracker);

    }

}

private static void DisplayTrackedEntities(DbChangeTracker changeTracker)

{

    Console.WriteLine("");

    var entries = changeTracker.Entries();

    foreach (var entry in entries)

    {

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

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

    }

    Console.WriteLine("");

    Console.WriteLine("

Find Student

Context tracking changes of  entity.

Entity Name: EFTutorials.Student

Status: Unchanged

---------------------------------------

Find Standard

Context tracking changes of  entities.

Editing Standard

Entity Name: EFTutorials.Standard

Status: Modified

Entity Name: EFTutorials.Student

Status: Unchanged

---------------------------------------

Adding New Teacher

Context tracking changes of  entities.

Entity Name: EFTutorials.Teacher

Status: Added

Entity Name: EFTutorials.Standard

Status: Modified

Entity Name: EFTutorials.Student

Status: Unchanged

---------------------------------------

Remove Student

Entity Name: EFTutorials.Teacher

Status: Added

Entity Name: EFTutorials.Standard

Status: Modified

Entity Name: EFTutorials.Student

Status: Deleted

---------------------------------------