refreshing page until new data added to database - php

Question

I want to refresh a PHP page every few second with SetInterval(); and it stop refreshing the page if a data added to database. so, when it refreshing my PHP page, it always checking is there a new data added to the database or not..
I'm trying to use this kind of logic but its not working...
$query = mysql_num_rows(SELECT id_example FROM table_example);
$a = count($query);
$b = $a+1;
IF($a==$b)
{
Stop_refreshing_the_page;
}
else
{
Refresh_with_setInterval();
}
is there anyone can suggest me better logic/algorithm/code example to do that??

Answer 1

Which part is not working?
Also, setInterval is probably not what you want if you are refreshing the entire page each time -- seems like a simple setTimeout and reload would do the trick, then simply not print that when you have db results.
Edited for OP
I assume this is not valid PHP, but you should get the idea.
$previous_count = $_GET['previous_count'];
$query = mysql_num_rows(SELECT id_example FROM table_example);
$result_count = count($query);
if ($previous_count == $result_count)
{
// this should render some javascript on the page including $result_count
}
The resulting javascript would be something like:
<script type='text/javascript'>
window.setTimeout( function(){
window.location = window.location.pathname + "?previous_count=<?php echo $previous_count; ?>";
}, 2000);
</script>