[Zope] linking zope/CMF objects to sql databases?

I need a content management system which acts as an operation and maintenance manual for assets. I need to be able to pull related data from a SQL database and update the SQL database by linking to some plone/zope object like folder id or possibly asset number as a value in the property of plone/zope objects. For example, if I have a record in the sql database, I want to allow users to add documentation, images, and other things to the plone folder and have it relate to the sql data for that asset ID. How might this be done? Is there an existing product? Is there a better way to relate this data? Anybody tried this? thanks, Sean