? ???? ??? ?????? ???? ?? ???? ?? ?? ? ??? ???? ?? ???? ?? ???? ???? ??? ??? ???? ?? ??? ???? ???? ???? ??? ??? ? ???.Datalog is usually a declarative logic programming language. Although it truly is syntactically a subset of Prolog, Datalog frequently employs a base-up instead of top-down evaluation model.Obtaining ISO 9001 certification is largel