Requête BDD avec PDO (en PHP)

<?php
/* Connexion avec PDO
$dsn = 'mysql:dbname=mabase;host=localhost';
$user = 'user';
$password = 'password';

try
{
    $dbh = new PDO($dsn, $user, $password);
}
catch(PDOException $e)
{
    echo 'ERREUR Connexion : ' . $e->getMessage();
}

/* Requête sécurisée */
$sql = 'SELECT * FROM table_news WHERE author = :author';
$fields = ['author' => 'Tom'];

$req= $dbh->prepare($sql, [PDO::ATTR_CURSOR => PDO::CURSOR_FWDONLY]);

$req->execute($fields);
$datas = $sth->fetchAll();