Include code from database?

Is there any easy way to store PHP / HTML code in a database, and pull it into a running PHP script? I'd like to build a template- based system where every page is generated by a single script, which pulls page-specific content from a MySQL database. But I can't figure out how to include PHP code "on the fly," or if it's even possible. I'm thinking the script will probably have to create a temporary file on the local system, building it with the template and the content pulled, and then include() it; this seems exceedingly resource-intensive, however, and I'd like to find a better way. (I could do it on a RAM disk, but this is a shared box that I rent space on, so I don't have root access to set something like that up.) Thanks in advance! Chris