Description:
------------
when I use "ROWNUM" as bind variable name,
the query result set doesn't appeared.


db:  oracle 8.1.7.4
db os: aix 5.3

webserver: apache 2.0.55
webserver os: winows 2000

php : 5.1.0



Reproduce code:
---------------
<?php
$dbh = new PDO("oci:dbname=sslgm166_8174", 'XXX', 'XXX',array(PDO::ATTR_PERSISTENT => true));
echo "<pre>";
$sql = 'select * from  tab where rownum < :ROWNU';
$sth = $dbh->prepare($sql);
$sth->execute(array(':ROWNU' => 2));
$result = $sth->fetchAll();
print_r($result);

echo "<hr>";
$sql = 'select * from  tab where rownum < :ROWNUM';
$sth = $dbh->prepare($sql);
$sth->execute(array(':ROWNUM' => 2));
$result = $sth->fetchAll();
print_r($result);
echo "</pre>";
?>

Expected result:
----------------
Array
(
    [0] => Array
        (
            [TNAME] => CREDITS
            [0] => CREDITS
            [TABTYPE] => TABLE
            [1] => TABLE
            [CLUSTERID] => 
            [2] => 
        )

)
-----------------------------------------
Array
(
    [0] => Array
        (
            [TNAME] => CREDITS
            [0] => CREDITS
            [TABTYPE] => TABLE
            [1] => TABLE
            [CLUSTERID] => 
            [2] => 
        )

)

Actual result:
--------------
Array
(
    [0] => Array
        (
            [TNAME] => CREDITS
            [0] => CREDITS
            [TABTYPE] => TABLE
            [1] => TABLE
            [CLUSTERID] => 
            [2] => 
        )

)
-----------------------------------------
Array  <------------------- EMPTY ARRAY !!!
(

)