About 'College Math Resources' - Technical Details

The site is based on a MySQL database accessed through PHP. These tools were chosen because they are free and effective (which are also the characteristics that we are looking for in what we collect).  There is no need for the high level security features or for the high volume scalability and collision avoidance that might be necessary in an airline reservation system (although I gather that MySQL is in fact used in a number of "mission-critical" commercial applications). So there is no reason for developing in an expensive medium like Oracle which might be a barrier to sharing development with other interested parties.

The database includes tables of topics, items, and reviews.
The topics are related by a dependency table which establishes a tree-like heirarchy. This is intended to model the typical user's mental model of the subject, and so to facilitate searching for materials (and if the current options and their relationships are inadequate it is easy to extend them).
The items table contains just ID, url and title fields. The effective metadata is provided by the reviews database which links items to topics. No standard metadata is collected as this is the responsibility of the url to provide (and in general has little overlap with what this user cares about when searching).
The reviews table provides links between items and topics which can be qualified by strength (relevancy) and quality, and also includes fields for comments and reviewer identification.

Implementation methods are by whatever I could make work (or at least seem to). As I am not an expert in either databases or php programming, any more specific details are not likely to be useful to anyone not charged with repairing this system.