One of the most useful things about relational databases is the ability to create parent-child relationships in a single table. An example of this is on the ASP Techniques (asptechniques.com) web site. Each category is either a root-level category or is a subcategory of another. This is all done with a single table, where each record has a foreign key to its parent.
The Bill of Materials Structure refers to this type of setup. Part 1 is composed of parts 2 and 3, each of which is composed of other components. In this article at ASP Today, you learn how to build this structure and make it work in your application.
<a href="http://www.asptoday.com/articles/20000516.htm">http://www.asptoday.com/articles/20000516.htm</a>