Chris Date’s book “An Introduction to Database Systems” is a good place to start. It focuses on relational databases, which reflects the dominance of relational

Chris Date’s book “An Introduction to Database Systems” is a good place to start. It focuses on relational databases, which reflects the dominance of relational database systems for decades now. Wikipedia has a decent article with history: https://en.wikipedia.org/wiki/Database https://en.wikipedia.org/wiki/Database Before relational database systems we had a lot of proprietary setups based on disk files. There were the variants of the hashing-based Pick database. There was CODASYL, and IBM’s IMS. Relational databases pretty much replaced all of those, though Pick-style systems are still running here and there. https://en.wikipedia.org/wiki/Pick_operating_system https://en.wikipedia.org/wiki/Pick_operating_system