Re: Relational Algebra and Aggregate Functions

On Sun, 2009-07-26 at 15:36 -0400, Robert James wrote:
> I'm working on improving my background database theory, to aid in
> practice.  I've found learning relational algebra to be very helpful.
>  One thing which relational algebra doesn't cover is aggregate
> functions.  Can anyone recommend any papers or web pages which provide
> some good theoretical background for aggregate functions?

When it comes to relational theory, C.J. Date is a good author. "An
Introduction To Database Systems" covers pretty much everything.

There's a formal definition of a relational algebra (including
SUMMARIZE, which is the authors' version of an aggregate operator)
defined with only two operators here:
http://thethirdmanifesto.com/
(look for "Appendix A")

Although Appendix A is not easy to understand without some basic
familiarity with the authors' other works.

Regards,
    Jeff Davis