' AUFRUF
Sub Button_Click([....])
        Dim ParentId As Int32 = Me.GetLastId + 1
End Sub
 
' FUNKTION
  Function GetLastId() As Int32
        Dim s As String = "SELECT MAX(ID) AS LAST_ID FROM Tabelle WHERE ID > 0;"
        Dim cmd As New OleDb.OleDbCommand(s, New OleDb.OleDbConnection( _
          "DEIN_CONNECT_STRING"))
        Dim rs As OleDb.OleDbDataReader
        Try
            rs = cmd.ExecuteReader
            rs.Read()
            Return Convert.ToInt32(rs("LAST_ID"))
        Catch ex As Exception
            Throw New Exception(ex.Message)
            Return -1
        Finally
            s = Nothing : cmd = Nothing : rs = Nothing
        End Try
    End Function