public ActionResult Xoa(int id)
        {
            GIAYCHUNGTHUC gcthuc = db.GIAYCHUNGTHUCs.Find(id);

            if (gcthuc != null)
            {
                db.GIAYCHUNGTHUCs.Remove(gcthuc);
                db.SaveChanges();
                int id_hs = (int)Session["id_hsDetail"];
                Session["chuyenTab"] = 8;
                return(RedirectToAction("DetailChung", "HocSinh", new { id = id_hs }));
            }
            return(View());
        }
        public JsonResult CapNhatGCT()
        {
            if (System.Web.HttpContext.Current.Request.Files.AllKeys.Any())
            {
                var file = Request.Files["HelpSectionFile"];
                //lưu tên file
                var fileName = Path.GetFileName(file.FileName);
                //lưu đường dẫn
                var path = Path.Combine(Server.MapPath("~/Content/filePDF"), fileName);
                // file is uploaded
                var type = file.ContentType;
                if (System.IO.File.Exists(path))
                {
                    ViewBag.Thongbao = "File đã tồn tại";
                }
                else
                {
                    if (type == "application/docx" || type == "application/pdf")
                    {
                        file.SaveAs(path);
                    }
                }
                Session["file"] = fileName;
                int id_HS = (int)Session["id_hsDetail"];
                if (id_HS != null)
                {
                    GIAYCHUNGTHUC giay = new GIAYCHUNGTHUC();
                    giay.Anh     = fileName;
                    giay.TenGiay = fileName;
                    giay.id_HSHS = id_HS;
                    db.GIAYCHUNGTHUCs.Add(giay);
                    db.SaveChanges();
                }

                return(Json(fileName, JsonRequestBehavior.AllowGet));
            }
            Session["file"] = null;
            return(Json("Khong", JsonRequestBehavior.AllowGet));
        }