I learned a big part from 'An introduction to Database Systems' from C.J.Date. The core understanding of relational databases is in there. It was at the time a book that needed cleaning up and reorganizing, but a few editions have passed by now, so maybe that has happened.
I also learned a lot of Tom Kyte's Expert 1 on 1. Beware: A huge tome, not only good for swatting flies, it can manage small rodents as well. I had the first or second edition which is probably pretty dated by now, but it is a good book to pick up the DBA attitude and learn advanced querying. If you use it as inspiration and not as a reference, it will probably still work.
Even if the 2nd book is about Oracle, I would suggest to start learning postgres, it is a cleaner, better structured database today.
I learned a big part from 'An introduction to Database Systems' from C.J.Date. The core understanding of relational databases is in there. It was at the time a book that needed cleaning up and reorganizing, but a few editions have passed by now, so maybe that has happened.
I also learned a lot of Tom Kyte's Expert 1 on 1. Beware: A huge tome, not only good for swatting flies, it can manage small rodents as well. I had the first or second edition which is probably pretty dated by now, but it is a good book to pick up the DBA attitude and learn advanced querying. If you use it as inspiration and not as a reference, it will probably still work.
Even if the 2nd book is about Oracle, I would suggest to start learning postgres, it is a cleaner, better structured database today.