You can convert this to a domain, but I'm still not sure how to say Julie likes everyone who likes girls. Using dependent data definitions in SQL gets very tric

You can convert this to a domain, but I'm still not sure how to say Julie likes everyone who likes girls. Using dependent data definitions in SQL gets very tricky very quickly. You can do it in a view, but a view is not designed to represent information, merely to present it. Assuming you could easily state that "Julie likes everyone who likes girls" once you converted the variable to a domain, you're still forced into a very rigid structure. If you're in a situation where a piece of knowledge in the database is unique for a given row, you wouldn't be able to convert everything to domains. Consider a situation where you're representing information about patients' blood tests. There are some basic tests that you can pigeonhole in a domain, but what about very specialized tests that only a handful of patients ever take? I think this is definitely a case of Blub for both of us. If we were to be set free from the relational way of thinking, we'd be solving problems we can't even think up now.