How to fetch data (messages) in every second with ajax (setinterval) from mysql (PHP) in wordpress?

Fetch data (messages) in every second with ajax (setinterval) from mysql (PHP) in wordpress.

In main file

<script>

jQuery(document).ready(function($){



var own_id = $("#own_id").val();
var user_id = $("#user_id").val();
alert('helo');


function sandeep(){

var data = {
'action':'fetch_message',
'own_id':own_id,
'user_id':user_id,
}


$.post(myajax.ajaxurl,data,function(response){
//$("#response").html(response);
$("#jassi").html(response);
console.log(response);
});


}


setInterval(function(){ sandeep(); }, 500);
});

</script>



<div id="jassi">



</div>

In Funtion.php file 

function fetch_message(){
$msg_content = $_POST['msg_content'];
$own_id = $_POST['own_id'];
$user_id = $_POST['user_id'];
echo $user_id;
global $wpdb;
$table_name13 = $wpdb->prefix . "user_chats";
$results = $wpdb->get_results("select * from $table_name13 where sender_id ='$own_id' AND receiver_id='$user_id'");
$total = count($results);

foreach($results as $result){
echo $result->msg_content."<br>";




}
die();
}

add_action('wp_ajax_nopriv_fetch_message','fetch_message');
add_action('wp_ajax_fetch_message','fetch_message');