booléen au lieu de tableau

<?php
    class ClassRDV {
        var $bdd;
        var $req;
        function __construct() {
            try {
                $this->bdd = new PDO('mysql:host=localhost; dbname=maDB; charset=utf8', 'root', 'root');
            } catch (Exception $e) {
                die('Erreur' . $e->getMessage());
            } 

                $this->req= $this->bdd->prepare('SELECT moment, client FROM rendezvous WHERE month(moment) = :month');
                $this->bdd->query('SET lc_time_names = \'fr_FR\'');
            }
        function getDates($month) {
            $tab = array();
            $ligne = $this->req->execute(array('month' => $month));
            while ($ligne->fetch()) {
                $tab[] = $ligne;
            }
            return $tab;
        }
    }
?>

<?php
function getDates($month) {
            $tab = array();
            $ligne = $this->req->execute(array('month' => $month));
            foreach ($this->req as $ligne) {
                $tab[] = $ligne;
            }
            return $tab;
        }