Visual Basic .NET Заполнение TreeView из базы данных без ограничения глубины вложения

Imports System.Data.OleDb
Public Class Form1
    Private Function GetDataTable() As DataTable
        Dim cnn As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\Test.mdb")
        Dim dAdapter As New OleDbDataAdapter("Select ID, Product, ParentID, ProductType From TableProduct", cnn)
        Dim rows As Integer
        Dim tblTemp As New DataTable
        Try
            rows = dAdapter.Fill(tblTemp)
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
        tblTemp.TableName = "TableSource"
        Return tblTemp
    End Function
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim tblSource As DataTable = GetDataTable()
        FillTreeView(TreeView1, tblSource)
        TreeView1.ExpandAll()
    End Sub
End Class
'**************************************************************************************
Module ModuleFillTreeView
    Private tvRoot As TreeNode
    Public Sub FillTreeView(ByVal sender As TreeView, ByVal TableSource As DataTable)
        Dim RowsRoot() As DataRow = TableSource.Select("ParentID=0", "Product")
        tvRoot = sender.Nodes.Add("#0", "Root")
        tvRoot.Tag = "Root"
        For Each dRow As DataRow In RowsRoot
            Dim NodeX As TreeNode = tvRoot.Nodes.Add("#" & dRow("ID"), dRow("Product"))
            WriteSubNode(NodeX, dRow("ID"), TableSource)
        Next
    End Sub
 
    Private Sub WriteSubNode(ByVal ParentNode As TreeNode, ByVal ParentID As Integer, ByRef tblSource As DataTable)
        Dim dRows() As DataRow = tblSource.Select("ParentID=" & ParentID, "Product")
        For Each dRow As DataRow In dRows
            Dim NodeX As TreeNode = ParentNode.Nodes.Add("#" & dRow("ID"), dRow("Product"))
            WriteSubNode(NodeX, dRow("ID"), tblSource)
        Next
    End Sub
'*********************************************************************************