if user is on page for more than 30 seconds, do something

OK, then on "initial page" you need something similar to:
window.onload=function(){
  setTimeout( "location.href='insert.php?status=exp&id=1';", 30*1000);  
}

then in insert.php
<?php
if( isset($_GET['status']) && "exp"==strval($_GET['status']) )
{
  mysql_connect("localhost","username","password") or die( mysql_error() );
  mysql_select_db("dbname") or die(mysql_error() );
  mysql_query( "insert into table (column1) values ('timeout') WHERE id=".inval($_GET['id']) ) or die( mysql_error() );
}
?>

i have the form on one page.   a form that posts to itself.  Is there any way to do this on one page

thanks