From Rosetta Code
DES is an implementation of Datalog. Other implementations of Datalog.

The Datalog Educational System (DES) is a free, open-source, multiplatform, portable, Prolog-based implementation of a basic deductive database system. DES 1.8.1 is the current implementation, which enjoys Datalog and SQL query languages, full recursive evaluation with memoization techniques, arithmetic, stratified negation and novel approaches to declarative debugging, test case generation for SQL views, null values support, (tabled) outer join and aggregate predicates. The system is implemented on top of Prolog and it can be used from a Prolog interpreter running on any OS supported by the Prolog interpreter. Moreover, Windows and Linux executables are also provided. The current release is only a bug-fix for binaries, which lacked some libraries avoiding to generate test cases.