Public Class frmDataExpression2
 
    Dim dt As New cDataTableCSV
 
    Dim bs As New BindingSource
    Dim dgv As New DataGridView With _
       {.Parent = Me, .DataSource = bs, _
        .Top = 50, .Width = 480, .Height = 400}
 
    'Filter-Controls
    Dim txtLaenge As New TextBox With _
        {.Parent = Me, .Width = 200}
    Dim txtBreite As New TextBox With _
        {.Parent = Me, .Width = 200, .Left = 210}
 
    Dim WithEvents btnFilter As New Button With _
        {.Parent = Me, .Left = 420, .Width = 100, .Text = "Filter"}
 
 
    Private Sub Form1_Load(sender As System.Object, _
        e As System.EventArgs) Handles MyBase.Load
 
        Me.Size = New Size(500, 500)
 
        If Not dt.LoadFile("C:\Daten\Numbers2.csv", System.Text.Encoding.UTF8) _
          Then
           MsgBox("Datei konnte nicht geladen werden")
        Else
           dt.Columns(0).ColumnName = "Laenge"
           dt.Columns(1).ColumnName = "Breite"
           bs.DataSource = dt
        End If
    End Sub
 
 
    Private Sub btnFilter_Click(sender As Object, _
        e As System.EventArgs) Handles btnFilter.Click
 
        Dim Laenge, Breite As Decimal, filter As String = String.Empty
 
        bs.Filter = "" 
 
        'ggf. erste Filterbedingung setzen
        If Decimal.TryParse(txtLaenge.Text, Laenge) Then
            filter = "Convert(Laenge, 'System.Decimal') = " & _
            Laenge.ToString(System.Globalization.CultureInfo.InvariantCulture)
        End If
 
        ggf. zweite Filterbedingung setzen
        If Decimal.TryParse(txtBreite.Text, Breite) Then
            'falls erste Bedingung gegeben --- Verknüpfung einschieben
            If Not filter = String.Empty Then filter &= " And "
 
            'zweite Bedingung setzen 
            filter &= "Convert(Breite, 'System.Decimal') = " & _
             Breite.ToString(System.Globalization.CultureInfo.InvariantCulture)
        End If
 
        'Filterstring zuweisen 
        bs.Filter = filter
 
    End Sub
End Class