การ Clear,Refresh ค่าใน Datagridview กับฐานข้อมูล MS Access !!!

 Private Sub Runnumber()
        Dim MaxID As Double
        Con.Open()
        Cmd = New SqlCommand()
        With Cmd
            .Connection = Con
            .CommandText = "SELECT MAX (Right(goodsID,3)) FROM GoodsReceive"
            If IsDBNull(.ExecuteScalar()) = True Then
                MaxID = 1
            Else
                MaxID = .ExecuteScalar() + 1
            End If
            txtautonum.Text = MaxID.ToString("000")
        End With
        Con.Close()