实体框架检查数据库表是否添加了新记录

我试图跟踪是否有可能，在实体框架中，检查数据库表是否添加了新记录。我试图从控制器获取记录，只有当有任何新记录添加到数据库表。任何建议吗?

服务器:

        [HttpGet]
        public JsonResult DisplayChatMsgs()
        {
            var chatMsgs = dbObj.tblChats.ToList();
            return Json(chatMsgs, JsonRequestBehavior.AllowGet);
        }

客户:

        $.ajax({
            url: "Default/DisplayChatMsgs",
            type: "Get",
            success: function (data) {
                //var mdata = $.parseJSON(data.d);
                //The Div to be populated
                $('#msgBox').empty();
                content = "";
                //Looping thru each record
                $.each(data, function (i, record) {
                    //Properties available in Model
                    //We need to specify the properties in our model
                    content += "<tr><td><b>" + record.toName + "</b>:</td><td>" + record.chatMsg + "</td></tr>";
                });
                table = "<table>" + content + "</table>"
                $(table).appendTo('#msgBox');
                $("#msgBox").animate({ scrollTop: $('#msgBox')[0].scrollHeight }, 1000);
            }
        });