public void AttachExample() { Console.WriteLine("Attach Example"); Department department1 = new Department(); department1.Name = "Production"; Department department2 = new Department(); department2.DepartmentID = 10; department2.Name = "Finance"; using (EFCoreContext db = new EFCoreContext()) { Console.WriteLine("Status Before Attach department1 " + db.Entry(department1).State.ToString()); //Detached Console.WriteLine("Status Before Attach department2 " + db.Entry(department2).State.ToString()); //Detached db.Attach(department1); db.Attach(department2); Console.WriteLine("Status After Attach department1 " + db.Entry(department1).State.ToString()); //Added Console.WriteLine("Status After Attach department2 " + db.Entry(department1).State.ToString()); //Unchanged db.Entry(department1).State = EntityState.Detached; Console.WriteLine("Status After Detach department1 " + db.Entry(department1).State.ToString()); //Added } Console.WriteLine("Press any key to continue "); Console.ReadKey(); }