I got the other problem: I've been away from SQL and databases too long to tell you. Set theory is one of those mathematical notations that can be used to model

I got the other problem: I've been away from SQL and databases too long to tell you. Set theory is one of those mathematical notations that can be used to model all kinds of things. They often prove out the simpler, easy-to-automate logics in more powerful ones like it. There's introductions to set theory online but here's what you might have not spotted: https://en.wikipedia.org/wiki/Set_theoretic_programming https://en.wikipedia.org/wiki/Set_theoretic_programming It was also used in formal specifications like Z. Also, used in one, verifying compiler that cheated the spec-to-code correspondence by straight-up turning the logical specs into executable Prolog. On database side, it would be Datalog for you to look into to explore logic programming + queries. Plenty of info out there on that with one DB (Datomic) built around it. https://en.wikipedia.org/wiki/Z_notation https://en.wikipedia.org/wiki/Z_notation http://www-users.cs.york.ac.uk/susan/bib/ss/hic/ http://www-users.cs.york.ac.uk/susan/bib/ss/hic/