public ActionResult Login(tblUser u)
        {
            if (ModelState.IsValid)
            {
                using (db_IMSEntities dc = new db_IMSEntities())
                {
                    try
                    {
                        var v = dc.tblUsers.Where(a => a.UserName.Equals(u.UserName) && a.Password.Equals(u.Password)).FirstOrDefault();

                        if (v != null)
                        {
                            int systemPosition = (int)v.SystemPosition;
                            Response.Cookies["systemPosition"].Value   = systemPosition + "";
                            Response.Cookies["systemPosition"].Expires = DateTime.MinValue;



                            Response.Cookies["userId"].Value   = v.UserId + "";
                            Response.Cookies["userId"].Expires = DateTime.MinValue;


                            string currentUserId = "" + v.UserId;
                            string filePath      = "~/File/currentUserId.txt";
                            WriteUserId(filePath, currentUserId);


                            return(RedirectToAction("defineRole", "System"));
                        }
                    }
                    catch (Exception e)
                    {
                        return(RedirectToAction("Login"));
                    }
                }
            }
            return(RedirectToAction("Login"));
        }