Function GetValue(ByVal o As Object, ByVal CurrentColumn As DataColumn) As _
      Object
        If o.Equals("") OrElse o Is Nothing OrElse o Is System.DBNull.Value Then
            Return CObj("{" + New String(" ", CurrentColumn.MaxLength) + "}")
        End If
        Return o
    End Function
    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button9.Click
        Dim sCon As String = "Provider=Microsoft.Jet.OLEDB.4.0;Password=;Data" & _
        "Source=Users.mdb;Mode=ReadWrite"
        Dim sSql As String = "SELECT * FROM Mitarbeiter WHERE IsNull(Vorname)"
        Dim da As New OleDb.OleDbDataAdapter(sSql, New OleDb.OleDbConnection( _
          sCon))
        Dim dt As New DataTable
        Dim r As DataRow
        da.FillSchema(dt, SchemaType.Source)
        da.Fill(dt)
        r = dt.Rows(0)
        MessageBox.Show(GetValue(r("Vorname"), r.Table.Columns( _
          "Vorname")).ToString)
 
End Sub