[judah]

This breaks down when you deal with classic object oriented concepts like inheritance, encapsulation, or polymorphism.

This is why object/relational mapping (ORM) has been called the Vietnam of Computer Science[0].

[0]: http://blogs.tedneward.com/post/the-vietnam-of-computer-scie...

[MarHoff]

Sorry if I was unclear, I'm not advocating for ORM.

And yes it breaks down because it is similar but different. Row "instances" can perfectly exists outside a table and even be defined outside any table via composites types or even on the fly.

Just saying a RDMS can be a powerful object-oriented environment using solely SQL and no ORM at all.