From Dhani's blog today, there's this new tutorial (part 1) showing you how to create a guest book for your site with PHP's help.

Proper development on any kind of project requires you to stop and evaluate the project before development begins (hopefully long before, but that's not always the case).

Having said that, let's figure out what we want the guestbook to do. What's the guestbook for? In this case, it's simply to let users view other visitor’s comments and to add their own. The guestbook is not a stand alone application - well it is, but it exists in the context of the web site

There's a few considerations mentioned before the code comes along (broken up into the business and technical sections). With the plan in place, Dhani shows the database layout chosen, the reasoning behind it, and the actual SQL you'll need to create it.