It wasn't quite as old, but there was an old MS DOS database system called Cosmos Revelation that was sort of a proto-nosql/graph database used keys and values for records, with the values being stored in long strings that contained field separators, and support for multiple values of the same time in a single field of a record. It used a language called R/BASIC that had library routines to help you work with the data structure.

This software is my retro computing white whale, I've never been able to find it. But I think it's evolved into a product called OpenInsight, by Revelation Software, which still exists.