I was intrigued by that statement as well and it sent me off on a little research excursion. Evidently a mathematician at MIT, David Spivak[0], has done some w

I was intrigued by that statement as well and it sent me off on a little research excursion. Evidently a mathematician at MIT, David Spivak[0], has done some work on Databases as Categories. I found a presentation he gave to Galois[1] and a summary of the talk by E.Z. Yang.[2]. That said, I think "tables synonymous with CT itself" is a bit strong. Rather, the argument is that database schemas are categories if you model it appropriately: tables are objects in the category, and foreign keys are the morphisms/arrows). [0] http://math.mit.edu/~dspivak/ http://math.mit.edu/~dspivak/ [1] http://math.mit.edu/~dspivak/informatics/talks/galois.pdf http://math.mit.edu/~dspivak/informatics/talks/galois.pdf [2] http://blog.ezyang.com/2010/06/databases-are-categories/ http://blog.ezyang.com/2010/06/databases-are-categories/