On the SitePoint PHP blog there's a new post introducing you to Redbean, a n ORM that can help you quickly prototype out applications that has a few tricks up its sleeve.
When it comes to RAD and prototyping, there are lots of tools available to help get projects up-and-running quickly. From quick-starts to micro-frameworks, from build tools such as Composer to one-click installers, and of course ORMs - there are all sorts of ways to speed up development time. I'm going to look at Redbean, an ORM with a difference, which is ideal for prototyping. Redbean is an ORM (Object Relational Mapper), but it does more than that - it creates and modifies the underlying schema on-the-fly.
He walks you through the installation of the library (well, links to this page on their site) and shows you how to "dispense" your first "bean" object. There's also some examples of saving objects, creating new ones and searching using the "load" method. Any good ORM also includes the ability to define relations, and Readbean is no exception - examples of this are also included. There's also a quick bit at the end about making models and querying the database directly with a SQL string.