Unfortunately, this use of the word relation, while I agree correct, has fallen out of favour, I think because it is confusingly similar to relationship, and because table is used everywhere instead (except academia.)
I'm not sure I understand what you mean about pointers though. I'd agree that if you have literal memory pointers, then you have an object database or a graph/network database. But entries in a relation based on values of candidate keys of another relation (that is, foreign keys) fit exactly within the relational algebra (natural join).
I don't see how information hiding in OO is analogous to not calling a database relational.
I'm not sure I understand what you mean about pointers though.
I'm talking about the practice, widespread in MySQL world, of all tables having a primary key of auto-increment integer.
There's nothing wrong, per se, with the example in the document as both Customer and Order are cases where an auto-integer is an appropriate primary key.
But I do think the reader could easily get the wrong idea, since the example consists of only those 2 tables.
Edit: Not that there's anything wrong with the practice. Just that your database is no longer a relational database. Knowing that fact and understanding why is, I think, a useful and educational thing for a student to understand.
this use of the word relation has fallen out of favour
Do you think that's true everywhere or just in web development world / MySQL world? I'd always guessed that, say, Oracle professionals know and understand the difference between "Chen--E/R model" and "Codd--relational database". But I'm not part of that world so I don't really know for certain.
I'm not sure I understand what you mean about pointers though. I'd agree that if you have literal memory pointers, then you have an object database or a graph/network database. But entries in a relation based on values of candidate keys of another relation (that is, foreign keys) fit exactly within the relational algebra (natural join).
I don't see how information hiding in OO is analogous to not calling a database relational.