The best book I've ever found so far is this one: https://www.springer.com/gp/book/9783030338350 https://www.springer.com/gp/book/9783030338350 The author buil

The best book I've ever found so far is this one: https://www.springer.com/gp/book/9783030338350 https://www.springer.com/gp/book/9783030338350 The author builds a small relational database from scratch in java. It supports only a few types and not all SQL commands but it's great to get a big picture.