使用php中的pdo与数据库链接服务器进行查询

I'm facing a problem right now, i explain :

I have my SQL query :

SELECT COUNT(*) AS nb, TO_CHAR(myDate,'yyyy-mm-dd') AS dateF, T1.IDCar, T2.IDMotor
FROM TDB2@MYLINKSERVER,T1
JOIN T2 ON T1.ID = T2.ID
WHERE TDB2.IDCar = T1.IDCar

Which use a TDB2@MYLINKSERVER , to connect 2 differents databases from Oracle and use a table from and other database.

In fact, when i launch the query in sql developper, my query returns some datas.

So in php, i have

$sql = $pdo->prepare('myquerybefore')
$sql->execute(array($annee));
$res = $sql->fetchAll(PDO::FETCH_ASSOC);

And when i try to vardump my $res, it returns array(0) { } So i think that PDO don't use the @LINKSERVER to fetch results.

Any help would be appreciated Sleakerz,

I found a way to make my query work : I create a synonym with

CREATE PUBLIC SYNONYM LINKDATABASE 
   FOR TABLE1@THELINKDATABASE;

Then i have in my query: FROM LINKDATABASE which is my synonym !