list<Model>判断用户是否存在，取出model只修改指定值

	   Dqt.Reporter.BLL.user UserBLL = new Dqt.Reporter.BLL.user();
            Dqt.Reporter.Model.user UserModel = new Dqt.Reporter.Model.user();
            List<Dqt.Reporter.Model.user> userlist = UserBLL.GetModelList("(UserName="" + txt_user_name.Text.Trim() + "" or Email="" + txt_user_name.Text.Trim() + "")" + " and UserPassword="" + MFunction.Md5HashString(txt_user_pwd.Text.Trim().ToString()) + """);
            if (userlist.Count > 0)
            {
                UserModel = userlist[0];
                UserModel.LastLoginIp = Request.UserHostAddress;
                UserModel.LastLoginTime = Util.TimeToUnixTimes(DateTime.Now.ToString());
                UserBLL.Update(UserModel);