I apologize if this question is on the wrong site, but hopefully I am asking this question on the correct site (and it's not, for example, for DBA professionals).
I am looking to learn a somewhat rigorous approach to relational algebra/calculus used for describing database theory. I already have a decent experience in the real-world with SQL and Database Design, but was wondering if there is a formal take on the mathematics behind it, and if so, a reference that I could use to self-teach.
It's also possible that this isn't a real math discipline worthy of a book/thesis-type discussion, in the same way that basic trigonometry could probably be covered in a few weeks in a Precalculus course and wouldn't require a full-length book to go over. (For reference, I have a background in calculus, linear algebra, and differential equations, so hopefully if it is its own math discipline I'll be suited to understanding it!) Thank you very much for your help and suggestions.