How to send null data to database if fileupload control is null in ASP.Net

Hi sir,

Below code i am using to save picture path in database in "@imagepath" column but sometime picture is not required and i am not uploading but still it is saving by default path like "Sightseeing-pics/pic42016". how to avoid it!

if (FileUpload1.PostedFile != null)
        {
            string FileName = Path.GetFileName(FileUpload1.PostedFile.FileName);

            FileUpload1.SaveAs(Server.MapPath("Sightseeing-pics/" + "pic" + string.Format("{0}{1}", DateTime.Now.Day, DateTime.Now.Year) + FileName));
            cmd.Parameters.AddWithValue("@imagepath", "Sightseeing-pics/" + "pic" + string.Format("{0}{1}", DateTime.Now.Day, DateTime.Now.Year) + FileName);

        }

<asp:FileUpload ID="FileUpload1" runat="server" />