The Datalog Educational System (DES) is a deductive database system with Datalog, SQL, and Relational Algebra as query languages.
Features in short:
- Free, open-source, multiplatform, portable, Prolog-based implementation.
- Extended Datalog (outer joins, aggregates, ordering, top-N answers, modes, ...)
- Extended SQL language (division relational operation, ...)
- Extended RA (recursion, ...)
- Integrity constraints
- Hypothetical reasoning
- Datalog and SQL declarative debuggers and tracers
- Test case generation for SQL views
- Textual API
- Stratified negation
- Full-fledged arithmetic