Mysql database update with ajax php not working

I am trying to update mysql database table with button click. But database is not getting updated...

HTML Code :

<tr >
<td>Advt Heading :</td>
<td>
<input type="hidden" name="idnew" id="idnew" value="<?=$member_data['id']?>"> //retrieved from mysql database 

<input type="text" name="advt_headingnew" id="advt_headingnew" value="<?=stripslashes($member_data['advt_heading']);?>" /> //retrieved from mysql database ...**I want to edit its previus retreived value...and update database**

<input name="submit" type="button" id="submit" value="Update" />

</td>
</tr>

SCRIPT :

<script src="http://code.jquery.com/jquery.min.js"></script>  
<script>
$(document).ready(function () { 
$('#submit').click(function(){
var advt_headingnew = $("#advt_headingnew").val();
var idnew = $("#idnew").val();


$.ajax({
     type:'POST',
     url:'update-advt-heading.php',
     data: "advt_headingnew="+advt_headingnew+"&idnew="+idnew,

     success:function( msg ) {
     alert( "Data Saved: " + msg );
        }

 });
});
});


</script>

PHP - update-advt-heading.php CODE :

<?
$user_name = "databaseusername";
$password = "databasepassword";
$database = "databasename";
$server = "localhost";

mysql_connect($server, $user_name, $password);
$db_found = mysql_select_db($database);

$heading = $_POST['advt_headingnew'];
$id=$_POST["idnew"];

if (isset($_POST['submit'])){


   $queryStr = "UPDATE tablename SET advt_heading='$heading' WHERE id='$id'";
    if ( mysql_query($qyeryStr)){
        return "success!";
    }else{
        return "failed!";
    }
}

?>

Copyright License：
Author:「Dr Manish Lataa-Manohar Joshi」,Reproduced under the CC 4.0 BY-SA copyright license with link to original source & disclaimer.
Link to：https://stackoverflow.com/questions/37364112/mysql-database-update-with-ajax-php-not-working