The example should be flexible enough to fit within different ORMs. Think of a scale from ActiveRecord to something really complicated like Java’s Hibernate – that’s the scale for the ORMs. It also needs to be really intuitive, so that the audience of the talk can understand it without much explanation – I want to focus on the ORMs themselves, not something else.

At this point, I’m leaning toward an example representing a user on a social network site and his friends. Something along these lines (don’t beat me up, it’s a very rough draft):

object model:

database model:

I think it’s a good idea to keep this example specific to functionality common in web applications (the alternative is kittens, really). On the other hand, I don’t want the example to be overly complex, so that the audience focuses more on the topic of the presentation rather than the details of the example.

When you come to presentations, what do you look for in examples? Are you looking for something you can basically copy and paste and use in your code? Or are you more interested in high-level theory where examples take a back seat and are there just for flavor but not really to explain?