Datalog - Notes

The Datalog (function-free) sublanguage of Horn logic is at the semantic foundation of RuleML. Datalog is the language in the intersection of SQL and Prolog. It can thus be considered as the subset of logic programming needed for representing the information of relational databases, including (recursive) views. That is, in Datalog we can define facts, corresponding to explicit rows of relational tables (extensional definition), and rules, corresponding to tables defined implictly by views (intensional definition).