MySQL Anzahl Strings mit selbem Beginn

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSearch.Click
        Dim conn As New MySqlConnection
        Dim myCommand As New MySqlCommand
        Dim myAdapter As New MySqlDataAdapter
        Dim mydatareader As MySqlDataReader
        Dim myString As String = ""  

        Dim SQL As String

        SQL = "SELECT * FROM artikel a, lagerbestand l, preisstaffel p, preiseinheit pr, me_tab m WHERE a.art_nr LIKE '" & txtArtikel.Text & _  
            "%' AND a.art_lfdnr = l.lbs_artlfdnr AND a.art_preisnr = p.mes_nr AND a.art_preiskz = pr.pr_nr AND a.art_mekz1 = m.me_nr"  

        conn.ConnectionString = myConnString
        Try
            conn.Open()
            Try
                myCommand = conn.CreateCommand()
                myCommand.CommandType = CommandType.Text
                myCommand.CommandText = SQL
                mydatareader = myCommand.ExecuteReader(CommandBehavior.SingleRow)
                mydatareader.Read()

                If mydatareader.HasRows Then

                    myString = mydatareader("art_nr")  
                    If Not IsDBNull(myString) Then
                        lblActiveArt.Text = Convert.ToString(myString)
                    End If

                    myString = mydatareader("art_bez_001")  
                    If Not IsDBNull(myString) Then
                        txtBez001.Text = Convert.ToString(myString)
                    Else
                        txtBez001.Text = String.Empty
                    End If
...

                End If
            Catch myerror As MySqlException
                MsgBox("Fehler beim Lesen der Datenbank: " & myerror.Message)  
            End Try
        Catch myerror As MySqlException
            MessageBox.Show("Fehler beim Verbindungsaufbau: " & myerror.Message)  
        Finally
            If conn.State <> ConnectionState.Closed Then conn.Close()
        End Try
    End Sub