setInterval(function(){
$("#some-container").load("schedule.php #some");
}, 2000);

<div id="some-container"></div>

Таблица user - id_user, name, avatar, rating
Таблица message - id_message, text
Таблица связи user~message - id_user, id_message

Select `user`.`name`, `message`.`text` From `message` INNER JOIN `user` ON (`user`.`id_user` = `message`.`id_user`) Where `message`.`id_user` = 2

https://codepen.io/gpyne/pen/iElhp