How to download file by click on link button in asp.net

string filename = "filename from Database";
Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition", "attachment;filename=" + filename);
string aaa = Server.MapPath("~/SavedFolder/" + filename);
Response.TransmitFile(Server.MapPath("~/SavedFolder/" + filename));
Response.End();