Symfony: Propel Custom Query

Here's sample Code

$connection = Propel::getConnection();
$query = 'SELECT MAX(?) AS max FROM ?';
$statement = $connection->prepareStatement($query);
$statement->setString(1, ArticlePeer::CREATED_AT);
$statement->setString(2, ArticlePeer::TABLE_NAME);
$resultset = $statement->executeQuery();
$resultset->next();
$max = $resultset->getInt('max')

Reference
08-Inside-the-Model-Layer