Add Select option to your Joomla select list

If you like to add 'Select Category' option to the option list you got from DB.

$db    =& JFactory::getDBO();
$query = "SELECT id as value,name as text FROM  categories WHERE parent_id > 0 ORDER BY name";
$db->setQuery($query);
$categories = $db->loadAssocList(); 
$begin_categories = array(array("value"=>0,"text"=>"Select Category"));
$categories = array_merge($begin_categories,$categories);
$lists['categories'] = JHTML::_('select.genericlist',  $categories, 'categories', 'class="inputbox" size="1"', 'value', 'text', null);

I am not sure any better way to do with Joomla classes.