使用pdo在php中显示内部联接结果

Question

我有这个问题，显示订单号，日期，数量，有效，并有来自validpersonel的内部联接名称。我怎样才能做到这一点？我的示例代码如下

include 'dbconnection.php';
session_start();

$id = $_SESSION['id']; //companyid
$p_id = $_SESSION['pId']; //personnelid
//$id = $_GET['p_id']
try{
    $sql="Select 
            ordermain.OrderNo,
            ordermain.OrderDate,
            validpersonnel.Name,
            ordermain.OrderedQTY,
            ordermain.Valid
        FROM ordermain 
                INNER JOIN validpersonnel ON ordermain.PersonnelID=validpersonnel.PersonnelID 
        WHERE ordermain.CompanyID = :id";

    $res=$db->prepare($sql);
    $res->execute(array('id'=> $id));
    //$res = $db->query($sql);
}       
catch(PDOException $e)
{
    die('There was an error.');
}
    $res->setFetchMode(PDO::FETCH_ASSOC);
    $result = $res->fetchAll();
    var_dump($result);