public ActionResult ChangeGroup(int id = 0)
        {
            var           daoUser      = new UserDao();
            var           daoUserGroup = new UserGroupDao();
            var           user         = daoUser.ViewDetail(id);
            List <string> result       = new List <string>();

            if (user.GroupID != null)
            {
                result = user.GroupID.Split(',').ToList();
            }
            var lstUserGroupFirst = daoUserGroup.GetUserGroup();
            Dictionary <string, string> lstGroupId = new Dictionary <string, string>();

            foreach (var item in result)
            {
                lstGroupId.Add(item, item);
            }
            TempData["lstGroupId"] = result;
            foreach (var role in result)
            {
                foreach (var item in lstUserGroupFirst.ToList())
                {
                    if (role.Trim() == item.ID.Trim())
                    {
                        lstUserGroupFirst.Remove(item);
                    }
                }
            }
            // show data có thể dùng ajax
            TempData["lstUserGroupFirst"] = lstUserGroupFirst;
            return(View(user));
        }