Dim orderId As Integer = 43680

Using context As New AdventureWorksEntities()
    Dim order = (From o In context.SalesOrderHeaders
            Where o.SalesOrderID = orderId
            Select o).First()

    ' Get ObjectStateEntry from EntityKey. 
    Dim stateEntry As ObjectStateEntry = _
        context.ObjectStateManager.GetObjectStateEntry(DirectCast(order, IEntityWithKey).EntityKey)

    'Get the current value of SalesOrderHeader.PurchaseOrderNumber. 
    Dim rec1 As CurrentValueRecord = stateEntry.CurrentValues
    Dim oldPurchaseOrderNumber As String = _
        DirectCast(rec1.GetValue(rec1.GetOrdinal("PurchaseOrderNumber")), String)

    'Change the value. 
    order.PurchaseOrderNumber = "12345"
    Dim newPurchaseOrderNumber As String = _
        DirectCast(rec1.GetValue(rec1.GetOrdinal("PurchaseOrderNumber")), String)

    ' Get the modified properties. 
    Dim modifiedFields As IEnumerable(Of String) = stateEntry.GetModifiedProperties()
    For Each s As String In modifiedFields
        Console.WriteLine("Modified field name: {0}", s)
        Console.WriteLine("Old Value: {1}", oldPurchaseOrderNumber)
        Console.WriteLine("New Value: {2}", newPurchaseOrderNumber)
    Next

    ' Get the Entity that is associated with this ObjectStateEntry. 
    Dim associatedEnity As SalesOrderHeader = DirectCast(stateEntry.Entity, SalesOrderHeader)
    Console.WriteLine("Associated Enity's ID: {0}", associatedEnity.SalesOrderID)
End Using

int orderId = 43680;

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    var order = (from o in context.SalesOrderHeaders
                 where o.SalesOrderID == orderId
                 select o).First();

    // Get ObjectStateEntry from EntityKey.
    ObjectStateEntry stateEntry =
        context.ObjectStateManager
        .GetObjectStateEntry(((IEntityWithKey)order).EntityKey);

    //Get the current value of SalesOrderHeader.PurchaseOrderNumber.
    CurrentValueRecord rec1 = stateEntry.CurrentValues;
    string oldPurchaseOrderNumber =
        (string)rec1.GetValue(rec1.GetOrdinal("PurchaseOrderNumber"));

    //Change the value.
    order.PurchaseOrderNumber = "12345";
    string newPurchaseOrderNumber =
        (string)rec1.GetValue(rec1.GetOrdinal("PurchaseOrderNumber"));

    // Get the modified properties.
    IEnumerable<string> modifiedFields = stateEntry.GetModifiedProperties();
    foreach (string s in modifiedFields)
        Console.WriteLine("Modified field name: {0}\n Old Value: {1}\n New Value: {2}",
            s, oldPurchaseOrderNumber, newPurchaseOrderNumber);

    // Get the Entity that is associated with this ObjectStateEntry.
    SalesOrderHeader associatedEnity = (SalesOrderHeader)stateEntry.Entity;
    Console.WriteLine("Associated Enity's ID: {0}", associatedEnity.SalesOrderID);
}