Código PHP:
<?
session_start();
if (!(isset($entrada))){
$_SESSION("entrada");
$conesion = mysql_connect("localhost","****","****");
mysql_select_db("****",$conesion);
$wasql = "update visitas set visitas = visitas +1 where id = 99";
mysql_query($wasql,$conesion);
$entrada=1;
}
mysql_close($conesion);
?>