Private Sub cmd_abgleich_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles cmd_abgleich.Click
        Dim fname_er As String
        Dim fname_belegnr As String
        Dim line_er As String = ""
        Dim line_belegnr As String = ""
        Dim belegnr_belegnr As String = ""
        Dim tmp_bn As ArrayList = New ArrayList
        Dim dbpath As String = System.IO.Path.Combine(Application.StartupPath, _
          "erhadb.mdb")
        Dim conn As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data" & _
        "Source=" & dbpath & ";")
        Dim sql As String = "SELECT * FROM tbl_belegnr;"
        Dim cmd As New OleDbCommand(sql, conn)
        Dim da As New OleDbDataAdapter(cmd)
        Dim ds As DataSet
 
        Dim MIX1 As String
        Dim belegnr As String
        Dim MIX2 As String
 
 
        fname_er = txt_er.Text
        fname_belegnr = txt_belegnr.Text
 
        Dim fs_er As FileStream = New FileStream(fname_er, _
          FileMode.OpenOrCreate, FileAccess.ReadWrite)
        Dim fs_bn As FileStream = New FileStream(fname_belegnr, _
        FileMode.OpenOrCreate, FileAccess.ReadWrite)
        Dim sr_er As StreamReader = New StreamReader(fs_er)
        Dim sr_bn As StreamReader = New StreamReader(fs_bn)
 
        If MsgBox("Es werden nun alle Daten der ER Datei in die Datenbank" & _
          "gespielt, und ein neuer Bestand erzeugt.", MsgBoxStyle.Information + _
          MsgBoxStyle.OkCancel) = MsgBoxResult.Cancel Then GoTo abort Else 
 
        Dim x As Decimal = 0
        Do While Me.Opacity > 0.5
            Me.Refresh()
            Me.Opacity -= 0.05
            For x = 1 To 100000
            Next x
        Loop
 
        Do While sr_bn.Peek <> -1
            line_belegnr = sr_bn.ReadLine()
            belegnr_belegnr = line_belegnr.Substring(0, 7)
            Try
                conn.Open()
                ds = New DataSet
                Dim row As DataRow = ds.Tables("tbl_belegnr").NewRow
                row("BELEGNR") = belegnr_belegnr
                ds.Tables("tbl_belegnr").Rows.Add(row)
                da.Update(ds, "tbl_belegnr")
 
            Catch ex As OleDbException
                MessageBox.Show(ex.Message, "Fehler", MessageBoxButtons.OK, _
                   MessageBoxIcon.Exclamation)
            Finally
                conn.Close()
            End Try
 
        Loop
 
 
        Do While sr_er.Peek <> -1
            line_er = sr_er.ReadLine
            MIX1 = Mid(line_er, 1, 11).Trim
            MsgBox(MIX1)
            belegnr = Mid(line_er, 12, 7).Trim
            MsgBox(belegnr)
            MIX2 = Mid(line_er, 19, 235).Trim
            MsgBox(MIX2)
 
        Loop
abort:
    End Sub