Dim dt As New DataTable
        Dim ParentId As Integer
        Dim tn As TreeNode
        ' dt mit einem "SELECT * FROM TreeNodes ORDER BY ID" füllen
        For Each r As DataRow In dt.Rows
            tn = New TreeNode(r("Text").ToString)
            ParentId = r("Parent")
            Dim dr() As DataRow = dt.Select("ParentNode=" & ParentId, "ID")
            For Each _r As DataRow In dr
                tn.Nodes.Add(_r("Text"))
            Next
            Me.TreeView1.Nodes.Add(tn)
        Next