____ v2 (there was no v1) was the first commercially available SQL-based relational database management system (6)
I believe the answer is:
oracle
(Other definitions for oracle that I've seen before include "Agent of divine revelation" , "Source of divine advice" , "Person of great wisdom, as in Delphi of old" , "Ancient Greek expounder of wisdom" , "Holy place in ancient times where gods prophesied" .)