How to know last autoincrement id in xml file

[Nareshmnt]

Hi, below my xml file

- - 1
DAK081012093349

Appetizers

Veg
South-Indian
Vankaya Bajji
Half Tray
12

• 2
  DAK081012093811

Appetizers

Veg
South-Indian
Aloo Vada
Half Tray
18

• 3
  DAK081012093811

Appetizers

Veg
South-Indian
Vankaya Bajji
Half Tray
20

below auto increment code

Dim xmldoc As New XmlDocument()
Dim Str_XmlFile As String = ""
Str_XmlFile = Server.MapPath("~/CatOrders/") & "CateringOrder.xml"

       If Not File.Exists(Str\_XmlFile) Then
           Dim StrWriter As New XmlTextWriter(Str\_XmlFile, System.Text.Encoding.UTF8)
           StrWriter.WriteStartDocument(True)
           StrWriter.WriteStartElement("CateringOrders")
           StrWriter.WriteEndElement()
           StrWriter.Close()

       End If
       xmldoc.Load(Str\_XmlFile)

       Dim parentelement As XmlElement = xmldoc.CreateElement("orders")
       Dim nodes As XmlNodeList = xmldoc.SelectNodes("//orders/userid")

       Dim nNodeID As Integer = nodes.Count
       nNodeID += 1
       Dim userid As XmlElement = xmldoc.CreateElement("userid")
       userid.InnerText = nNodeID
       Dim orderid As XmlElement = xmldoc.CreateElement("orderid")
       orderid.InnerText = Session("orderid")

please let me know how to get last unique id

[Christopher Drake]

I write in c#, but you should be able to use the xpath to get the last unique orderid from your xml.

static void Main(string[] args)
{
XmlDocument doc = new XmlDocument();
doc.Load(@"c:\temp\cateringorders.xml");
string query = "(//orderid[not(orderid=preceding-sibling::orderid)])[last()]";
XmlNodeList nodes = doc.SelectNodes(query);
foreach (XmlNode node in nodes)
{
Console.WriteLine(node.InnerText);
}
Console.WriteLine("Finished");
}