jQuery AJAX更改警报

Question

How to alert if another data added to the database? in this case everysecond there is an alert how can i apply this to have a notification when another data is fetched.

$(document).ready(function() {
    setInterval(function() {
        $.get('functions/today_sched.php', function (data) {
            $('#today').html(data);
            alert('change')
        });
    }, 1000); 
});

HTML

<div id = "today"></div>

today_sched.php

<?php 
                $con = mysqli_connect("localhost","root","","schedule");
                $date = date("d/m/Y");

                $count=1;
                $sel_query="Select * from today_schedule where date = '$date'";
                $result = mysqli_query($con,$sel_query);



                while($row = mysqli_fetch_assoc($result)) {
                <tr>
                  <td>echo $row['date'];</td> 
                </tr>
                $count++;
                }
?>