Thanks! I will check Datalog out, i have never used it (though i know Prolog a bit).

So the main difference is then that my version is SQL based: alter table transactions add constraint c_amount check (amount > 10000 -> auth.name = user.man.name) # or something similar, where you refer to other tables via a chain of foreign keys.

Another extra feature is that you can use aggregators in constraints in case of a one to many relationship: https://github.com/gsvigruha/cosyan/blob/master/src/main/res...