One of the first C programs I wrote pulled data from an Ingres Database, all running on a PDP 11/34. I now use PostgreSQL heavily on AWS. Thanks Michael Stonebraker!
I'm still developing web services connected to an Ingres instance running on a rickety ~22 year old Sun server with lots of bits and pieces cannibalized from its long dead siblings.
We have the replacement system almost ready but won't really be able to swap the thing until the project owner retires (yay politics!).
It's important but not time-critical, so if it dies before he goes we can just eat the downtime and take a couple of weeks to migrate.