问无法在Doctrince中为原始SQL设置参数

EN

   //input datetime type for $dateStart,$dateEnd
    $start = date_format( $dateStart,'Y-m-d');
    $end = date_format( $dateEnd,'Y-m-d');  
       $sql = '
            SELECT 
            *
            FROM 
                    log 
            WHERE 
                    time >= "? 00:00:00" 
            AND 
                    time <= "? 23:59:59"
            ';
        $pdo = $this->em->getConnection();      
        $stmt = $pdo->prepare($sql);
        $stmt->bindValue(1,$start);
        $stmt->bindValue(2,$end);       

        $stmt->execute();
        $rs = $stmt->fetchAll();

$param = array($start,$end);