Upgrading The GreenTech Shop Database from Yahoo! E-Commerce to MySQL

I'm in the process of upgrading The GreenTech Shop database. Currently, The GreenTech Shop has been using a Yahoo! E-Commerce back-end (I'm not sure what RDBMS they use), but I just don't think that its flexible enough for to create a dynamic site that I envision.

For example, I want the radios section page to show all of the radios we have for sale in our database dynamically. So I'm going to have to write a simple query to select all radios where the product category equals radio. Simple enough right? The problem is that you can't access the Yahoo! E-Commerce back-end using SQL as far as I know. So I'm in the process of creating my own database which I can access using PHP. This will make the website more dynamic and I can start deleting all of those static pages that are pretty tedious to maintain.

I believe that you can do something like this using Yahoo's templates, but I'm not interested in learning their system. For whatever reason, probably prior experience, I still think that Yahoo's template will be flexible enough. At this point I rather build my own custom solution.