[PHP] Vérifier la présence d'une personne

<?php
$pdo = new PDO('mysql:host=localhost;dbname=ta_base','root','');

$sql = 'DELETE * FROM lectures WHERE pseudo = :pseudo';
$req = $pdo->prepare($sql);
$req->execute(array(':pseudo' => $_SERVER['PHP_AUTH_USER']));
$req->closeCursor();

$sql = 'INSERT INTO lectures(pseudo,date,page) VALUES(:pseudo,:date,:page)';
$req = $pdo->prepare($sql);
$req->execute(array(
    ':pseudo' => $_SERVER['PHP_AUTH_USER'],
    ':date' => $_SERVER['REQUEST_TIME'],
    ':page' => $_SERVER['PHP_SELF']
));
$req->closeCursor();
?>

<?php
$sql = 'SELECT pseudo FROM lectures WHERE date > '.($_SERVER['REQUEST_TIME'] - 300).' AND page = "'.$_SERVER['PHP_SELF'].'"';
$req = $pdo->query($sql);
while($row = $req->fetch(PDO::FETCH_OBJ)) {
    echo '<li>'.$row->pseudo.'</li>'."\n";
}
$req->closeCursor();
?>