How to call a Stored Procedure with 'out' parameter

[eluser]Unknown[/eluser]
[quote author="abdul mohsin" date="1321120954"]but i did not get how i can access the value of the OUT parameter and use in my php file>[/quote]

Code:

$sql = "call int_MapColumnToCustomFields(?,@x);";
        $params = array($id);
        $this->db->query($sql, $params);
$sqlGetOutParam = "SELECT @x;";
$outValue = $this->db->query($sqlGetOutParam);

echo "<pre>";
print_r($outValue->result());
echo "</pre>";

Hope you will get it.