Hierarchical data in a relational database

Hi All

Today an interesting article about how represents hierarchical data in a relational database.

 http://fungus.teststation.com/~jon/treehandling/TreeHandling.htm

Interesting this concept :

Every node must have a node identify and a "Child of" identify. So the key of every object is formed by two keys :

• ID_NODE
• CHILD_OF

For example (represents image above) :

ID_NODE  CHILD_OF
1	1
2	1
3	1
4	2
5	3
6	5

Stay tuned.