title: Entity framework doesn't save data entries in database
body: <p>At first I should mention that this problem only occurs in windows forms applications and the same program in web mode for example with MVC3 works perfect.</p>
  
  <p>Some days ago I wrote a very simple windows form program using Visual studio 2010 ultimate with a SQL Express database. I added the database by choosing Add > New item > Service-Based database and an entity data model based on this database in same way. I used Entity framework for adding some new records to tables. I had done such thing with VS 2008 SP1 before with no problem so I did the same. The program compiled and ran with no errors and I entered some new data. after exiting the program I came back to the database and nothing was happened. None of information I had entered had been saved.
  I debug the program step by step and everything was alright.
  The code below is related to a very simple program with mentioned problem. Database has one table (book):</p>
  
  <pre><code>namespace Book
  {
      public partial class BookForm : Form
      {
          BookDatabaseEntities db = new BookDatabaseEntities();
  
          public BookForm()
          {
              InitializeComponent();
          }
  
          private void saveButton_Click(object sender, EventArgs e)
          {
              Book bookToCreate = new Book();
  
              bookToCreate.Id = Guid.NewGuid();
              bookToCreate.Title = titleTextBox.Text;
  
              db.Books.AddObject(bookToCreate);
              db.SaveChanges();
          }
      }
  }
  </code></pre>
  
  <p>I'll be very grateful if anyone help me. Thanks in advance.</p>
  
  <p>.................</p>
  
  <p>After editing:</p>
  
  <pre><code>namespace Book
  {
      public partial class BookForm : Form
      {
          //BookDatabaseEntities db = new BookDatabaseEntities();
  
          public BookForm()
          {
              InitializeComponent();
          }
  
          private void saveButton_Click(object sender, EventArgs e)
          {
              var db = new BookDatabaseEntities();
              var bookToCreate = db.Books.CreateObject();
  
              //Book bookToCreate = new Book();
  
              bookToCreate.Id = Guid.NewGuid();
              bookToCreate.Title = titleTextBox.Text;
  
              db.AcceptAllChanges();
              db.Books.AddObject(bookToCreate);
              db.SaveChanges();
          }
      }
  }
  </code></pre>