DB_NestedSet pear.php.net Database PHP License API to build and query nested sets DB_NestedSet let's you create trees with infinite depth inside a relational database. The package provides a way to o create/update/delete nodes o query nodes, trees and subtrees o copy (clone) nodes, trees and subtrees o move nodes, trees and subtrees o Works with PEAR::DB, PEAR::MDB, PEAR::MDB2 o output the tree with - PEAR::HTML_TreeMenu - TigraMenu (http://www.softcomplex.com/products/tigra_menu/) - CoolMenus (http://www.dhtmlcentral.com/projects/coolmenus/) - PEAR::Image_GraphViz (http://pear.php.net/package/Image_GraphViz) - PEAR::HTML_Menu