[nigwil_]

In computing history claims like "first" and "commercial success" need to be qualified and defined, and therein things become difficult since timing and thresholds matter to meet a generally acceptable standard of either claim.

In the 1960s, several companies were selling commercial database management systems (as a distinct product), for example: IBM IMS, Univac DMS and General Electric IDS. These ideas were established to a level that there was a database standard committee known as CODASYL active from 1959 onward.

There is a good overview of the 1960s here: https://link.springer.com/content/pdf/10.1007/978-0-387-3474...