public static function fromDatabase()
{
$themen = new Themen();
$query = 'select parent, Name from Thema order by parent, Name;';
$result = mysql_query($query);
$allChilds = array();
while (list($parent, $child) = mysql_fetch_row($result)) {
$themen->add($parent, $child);
$allChilds[] = $child;
}
foreach ($themen->themen as $parent => $childs) {
if ($parent == Themen::ROOT_NAME) {
continue;
}
if (array_search($parent, $allChilds) === false) {
$themen->add(Themen::ROOT_NAME, $parent);
}
}
return $themen;
}
