Public Sub Kriterien_Export()
 
        Dim sql_Export As String
 
        sql_Export = "SELECT  EXPORT.DATUM, EXPORT.PERSNR, EXPORT.NAME," & _
          "EXPORT.VORNAME, EXPORT.STUNDEN, (select isnull(sum(erfasst),0) from" & _
          "v_erfasste_MA_Std where MA_nr = EXPORT.PERSNR and schichtdatum =" & _
          "EXPORT.DATUM) AS erfasst,"
        sql_Export &= "EXPORT.STUNDEN - (select isnull(sum(erfasst),0) from" & _
        "v_erfasste_MA_Std where MA_nr = EXPORT.PERSNR and schichtdatum =" & _
        "EXPORT.DATUM) AS offen from  "
        sql_Export &= " EXPORT where EXPORT.LOHNART = 'AWS' "
 
        Select Case Me.ComboBox_Persnr.Text.ToString
            Case Is <> "", Not IsNothing(Me.ComboBox_Persnr.Text.ToString)
                sql_Export &= " AND EXPORT.PERSNR ='" & _
                  Me.ComboBox_Persnr.Text.ToString & "'"
 
' -----------------------------------------------------------------------------
' Hier ist das Problem ...
' -----------------------------------------------------------------------------
                Select Case Me.ComboBox_Datum.Text.ToString
                    Case Is <> "", Not IsNothing( _
                      Me.ComboBox_Datum.Text.ToString)
                        sql_Export &= " AND EXPORT.DATUM = '" & CType( _
                        Me.ComboBox_Datum.Text(), Date) & "'"
                    Case Else
                        sql_Export &= ""
                End Select
 
' ------------------------------------------------------------------------------
 
            Case Else
                Select Case Me.ComboBox_Datum.Text
                    Case Is <> "", Not IsNothing(Me.ComboBox_Datum.Text)
                        'Me.ComboBox_Datum.Text = Nothing
                        'sql_Export &= " AND Export.datum = '" & ( _
                          Me.ComboBox_Datum.Text.ToString) & "'"
                        sql_Export &= " AND Export.datum = '" & CType( _
                        Me.ComboBox_Datum.Text(), Date) & "'"
                        'sql_Export &= " AND Export.datum = '" & CType( _
                        Me.ComboBox_Datum.Text(), Date) & "'"
                    Case Else
                        sql_Export &= ""
                End Select
        End Select
 
        ' --- DataAdapter-Instanz bilden (Verbindung zur DB benennen) 
        ' --- und SelectCommand übergeben
 
        da_Adapter = New SqlDataAdapter("", conn)
        da_Adapter.SelectCommand.CommandText = sql_Export
        da_Adapter.SelectCommand.CommandType = CommandType.Text
 
        ' *** DataSet und DataTable-Instanz bilden
        ds_PZE = New DataSet("PZE")               ' DataSet-Instanz bilden
        dt_Export = New DataTable("Export")       ' DataTable-Instanz bilden
        ds_PZE.Tables.Add(dt_Export)
 
        ' --- Primärschlüssel-Informationen beim Fill mit übernehmen
        da_Adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey
 
        ' --- DataTable füllen
        da_Adapter.Fill(dt_Export)
 
        ' --- DataView-Instanz für DataTable bilden
        dv = New DataView(dt_Export)
 
        ' --- ggfs. Filter eintragen
        'dv.RowFilter = "Datum = " & Me.ComboBox_Datum.Text
        'dv.Sort = "Zuname ASC"
 
        ' --- Datenbindung an DataGridView_Export
        With DataGridView_Export
            ' Standard-Hintergrundfarbe
            .RowsDefaultCellStyle.BackColor = Color.White
            ' Altern. Hintergrund
            .AlternatingRowsDefaultCellStyle.BackColor = Color.LightSteelBlue
            .RowHeadersVisible = False
            .DataSource = dv
            .Refresh()
            .Show()
        End With
 
        ' Formatierungen DataGridView_Export
 
        With Me.DataGridView_Export.Columns(0)    ' EXPORT.DATUM
            .Width = 65
            .DefaultCellStyle.Format = "d"
        End With
 
        With Me.DataGridView_Export
            .Columns(1).Width = 60              ' EXPORT.PERSNR
            .Columns(2).Width = 90              ' EXPORT.NAME
            .Columns(3).Width = 90              ' EXPORT.VORNAME
        End With
 
        For i = 4 To 6
            With Me.DataGridView_Export.Columns(i)    ' EXPORT.STUNDEN
                .Width = 62
                .DefaultCellStyle.Alignment = _
                  DataGridViewContentAlignment.MiddleRight
                .DefaultCellStyle.Format = "#,##0.00"
            End With
        Next
 
    End Sub