$select = "SELECT * FROM `jos_users`";

$connection->setQuery($select);

$rows = $connection->getNumRows();

$rows doesn't work it throws the 'mysql_num_rows(): provided argument isn't a valid' error but...

$result = $connection->loadObjectList();

$result works fine.

Is a Joomla bug?? Or what shall we be held doing wrong?

<?
$select = "SELECT * FROM `jos_users`";

$connection->setQuery($select);

//add this:
$connection->query();

$rows = $connection->getNumRows();
?>

You are setting the query although not performing it.

wouldn't it have to call query()... $res = $db->query('select * from jos_users') $db->getNumRows($res)