IBM i (nee AS/400) also uses a database for its lower layers, and even though it isn't that common, database systems like MS SQL Server and Oracle can also be fully used to write applications with Web UIs, e.g. APEX, or mapping Web API endpoints to stored procedures.
They can also make use of raw partitions, thus having a server that is all about the RDMS and nothing else.
And PICK is still kind of around! Today the “multi value” database torch is in the hands of Rocket Software, which licenses it as “UniData” and “UniVerse”. Most of the logic for the higher ed ERP software Colleague relies on the BASIC flavor “UniBasic”, which is heavily tied to the MV database, for application logic.
Still used under the hood by two major auto dealership computer systems, for example (UniVerse in the Reynolds and Reynolds ERA DMS and a fork of Northgate Reality in the CDK DMS).
I hadn't heard of this before and found it really interesting and entertaining. This reminds me of the Ediacaran and Cambrian critters... where one looks at fossils of things like Hallucigenia and marvels at the different paths that evolution could've taken.
The video called me out when it mentioned that the query language might seem scary or dirty to some of us - and it does! My eyelid twitched when I saw the example on screen - but it's still really interesting to me to think about a database as the source of the OS primitives, rather than an application running within a more standard OS and using the OS's conceptual framing.
Asianometry has a good number of these technical, interesting, and to-the-point videos about various technologies (e.g. a good one about Lisp machines). I haven't watched _many_ of them, but the ones I've watched were definitely worth the time.
i used to predict Datalog would win out eventually but sadly was wrong.
SQLite callbacks let you implement anything you please inside the scope of transactions, triggers, other events etc. To make an app run this way all you need is a starting event. You could implement an OS this way, heheh.
My uncle, a very tech-savvy accountant type, used it a lot back in the day and always had nice things to say about it.