Whether you want to build your own forum, publish the messages from a mailing list on your Website, or write your own cms [1]: there will be a moment that you’ll want to store hierarchical data in a database. And, unless you’re using a XML [2]-like da
S. Bozza, and A. O'Hagan. Between Data Science and Applied Data Analysis: Proceedings of the 26th Annual Conference of the Gesellschaft Fűr Klassifikation Ev, 26, page 165. University of Mannheim, Springer Verlag, (2003)