Ошибка: Warning: mysqli_num_rows() expects parameter 1 to be C/... on line 7

Код:

1.<?php
2.    $link = mysqli_connect('localhost', 'root', '', 'chat');
3.    $sql = "SELECT * FROM 'messages' ORDER_BY 'date'";
4.    $results = mysqli_query($link, $sql);
5.
6.    if(!isset($_GET['add_message'])) {
7.       if (mysqli_num_rows($results) >= 1) {
            while ($out = mysqli_fetch_assoc($results)) {
                echo $out['name']." | ".$out['date']."<br>".$out['message']."<hr>";
            }
        }
    }