I like the Modified Preorder Tree Traversal Algorithm. This technique makes it very easy to query the tree.
But here is a list of links about the topic which I copied from the Zend Framework (PHP) contributors webpage (posted there by Posted by Laurent Melmoux at Jun 05, 2007 15:52).
Many of the links are language agnostic:
There is 2 main representations and algorithms to represent hierarchical structures with databases :
- nested set also known as modified preorder tree traversal algorithm
- adjacency list model
It’s well explained here:
- http://www.sitepoint.com/article/hierarchical-data-database
- Managing Hierarchical Data in MySQL
- http://www.evolt.org/article/Four_ways_to_work_with_hierarchical_data/17/4047/index.html
Here are some more links that I’ve collected:
- http://en.wikipedia.org/wiki/Tree_%28data_structure%29
- http://en.wikipedia.org/wiki/Category:Trees_%28structure%29
adjacency list model
- http://www.sqlteam.com/item.asp?ItemID=8866
nested set
- http://www.sqlsummit.com/AdjacencyList.htm
- http://www.edutech.ch/contribution/nstrees/index.php
- http://www.phpriot.com/d/articles/php/application-design/nested-trees-1/
- http://www.dbmsmag.com/9604d06.html
- http://en.wikipedia.org/wiki/Tree_traversal
- http://www.cosc.canterbury.ac.nz/mukundan/dsal/BTree.html (applet java montrant le fonctionnement )
Graphes
- http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html
Classes :
Nested Sets DB Tree Adodb
- http://www.phpclasses.org/browse/package/2547.html
Visitation Model ADOdb
- http://www.phpclasses.org/browse/package/2919.html
PEAR::DB_NestedSet
- http://pear.php.net/package/DB_NestedSet
- utilisation : https://www.entwickler.com/itr/kolumnen/psecom,id,26,nodeid,207.html
PEAR::Tree
- http://pear.php.net/package/Tree/download/0.3.0/
- http://www.phpkitchen.com/index.php?/archives/337-PEARTree-Tutorial.html
nstrees
- http://www.edutech.ch/contribution/nstrees/index.php