Bagaimana saya bisa menolak semua perubahan dalam Linq untuk SQL's DataContext?

public static class DataContextExtensions
{
    /// 
    ///     Discard all pending changes of current DataContext.
    ///     All un-submitted changes, including insert/delete/modify will lost.
    /// 
    /// <param name="context">A value that specifies how optimistic concurrency conflicts are handled.

dataContext.Refresh(RefreshMode.OverwriteCurrentValues, someObject);

foreach (Customer c in MyDBContext.GetChangeSet().Updates)
        {
            MyDBContext.Refresh(System.Data.Linq.RefreshMode.OverwriteCurrentValues, c);
        }

Public Sub DiscardInsertsAndDeletes(ByVal data As DataContext)
    ' Get the changes
    Dim changes = data.GetChangeSet()

    ' Delete the insertions
    For Each insertion In changes.Inserts
        data.GetTable(insertion.GetType).DeleteOnSubmit(insertion)
    Next

    ' Insert the deletions
    For Each deletion In changes.Deletes
        data.GetTable(deletion.GetType).InsertOnSubmit(deletion)
    Next
End Sub

Public Sub DiscardUpdates(ByVal data As DataContext)
    ' Get the changes
    Dim changes = data.GetChangeSet()

    ' Refresh the tables with updates
    Dim updatedTables As New List(Of ITable)
    For Each update In changes.Updates
        Dim tbl = data.GetTable(update.GetType)
        ' Make sure not to refresh the same table twice
        If updatedTables.Contains(tbl) Then
            Continue For
        Else
            updatedTables.Add(tbl)
            data.Refresh(RefreshMode.OverwriteCurrentValues, tbl)
        End If
    Next
End Sub

var changes = db.GetChangeSet();
if ((changes.Updates.Count > 0) || (changes.Inserts.Count > 0) || (changes.Deletes.Count > 0))
{
    if (MessageBox.Show("Would you like to save changes?", "Save Changes", MessageBoxButton.YesNo)  == MessageBoxResult.Yes)
    {
        db.SubmitChanges();
    } else
    {
        //Rollback Changes
        foreach (object objToInsert in changes.Inserts)
        {
            db.GetTable(objToInsert.GetType()).DeleteOnSubmit(objToInsert);
        }
        foreach (object objToDelete in changes.Deletes)
        {
            db.GetTable(objToDelete.GetType()).InsertOnSubmit(objToDelete);
        }
        foreach (object objToUpdate in changes.Updates)
        {
            db.Refresh(RefreshMode.OverwriteCurrentValues, objToUpdate);
        }
        CurrentForm.SetObject(null); //Application Code to Clear active form
        RefreshList(); //Application Code to Refresh active list
    }
}

  public static bool UndoPendingChanges(this NtsSuiteDataContext dbContext)
  {
     if (dbContext.ChangesPending())
     {
        ChangeSet dbChangeSet = dbContext.GetChangeSet();

        dbContext.Refresh(RefreshMode.OverwriteCurrentValues, dbChangeSet.Deletes);
        dbContext.Refresh(RefreshMode.OverwriteCurrentValues, dbChangeSet.Updates);

        //Undo Inserts
        foreach (object objToInsert in dbChangeSet.Inserts)
        {
           dbContext.GetTable(objToInsert.GetType()).DeleteOnSubmit(objToInsert);
        }

        //Undo deletes
        foreach (object objToDelete in dbChangeSet.Deletes)
        {
           dbContext.GetTable(objToDelete.GetType()).InsertOnSubmit(objToDelete);
        }
     }

     return true;
  }