php ile pdo sınırsız kategori nasıl yapılır

function categories_table($id = 0, $string = 0) { 
	global $database;
	$categories 	= $database->prepare("SELECT * from tm_categories where parentid= :id");
	$categories->bindParam(':id', $id, PDO::PARAM_INT);
	$categories->execute();
	$totalRowCat 	= $categories->rowCount();
	if(0 < $totalRowCat):
		foreach($categories as $category):
			if($category["parentid"]==0):
				$font='style="font-weight:bold !important;"';
				$folder = '<img src="img/folder.gif" />';
				$extrastring ="8";
				else:
				$extrastring ="3";
			endif;
			echo '
			<tr>
				<td class="text-center">'.$category["id"].'</td>
				<td '.@$font.'>'.str_repeat("&nbsp;", $string).' '.@$folder.' '.$category["title"].'<br /></td>
				<td><small><i>'.$category["description"].'</i></small></td>
				<td>
				<div class="btn-group">
                	<button class="btn btn-default btn-sm dropdown-toggle" type="button" data-toggle="dropdown">
                 	İşlem <span class="caret"></span>
                	</button>
                	<ul class="dropdown-menu">
                 	 <li><a href="dashboard.php?section=categories&action=categoryedit&id='.$category["id"].'&pid='.$category["parentid"].'">Düzenle</a></li>
                 	 <li><a href="dashboard.php?section=categoriess&action=dropcategory&id='.$category["id"].'">Sil</a></li>
                	</ul>
                </div>
				</td>
			</tr>';
			categories_table($category["id"], $string+5);
		endforeach; 
	endif;
}