- Bitemporal Databases: Modeling and Implementation: https://www.amazon.com/Bitemporal-Databases-Canan-Eren-Atay/...

- Developing Time-Oriented Database Applications in SQL by Rich. Snodgrass: https://www.amazon.com/Developing-Time-Oriented-Database-App...

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Anything by Joe Celko:

- SQL for Smarties: https://www.amazon.com/gp/product/B00R17NZZC

- SQL Programming Style: https://www.amazon.com/gp/product/B006L21AO6

- Trees and Hierarchies in SQL for Smarties: https://www.amazon.com/gp/product/B006Y8MKUU

- Thinking in Sets: https://www.amazon.com/gp/product/B001AODZZC

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- SQL Antipatterns by Bill Karwin: https://www.amazon.com/SQL-Antipatterns-Programming-Pragmati...

Some advice from the dark ages 20 years ago:

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 like Curious Moon, anything by C.J. Date, The Art of SQL, and if a course is wanted: Mastery with SQL.

That 'Curious Moon' actually seems pretty cool.

https://bigmachine.io/products/a-curious-moon/

Lex de Haan and Toon Koppelaars, Applied Mathematics for Database Professionals -- a fairly gentle introduction to database theory starting with logic & discrete math

Ralph Kimball and Margy Ross, The Data Warehouse Toolkit -- even if you're in an OLTP context, it's useful to know about warehousing techniques

Dmitri Fontaine, The Art of PostgreSQL -- cookbook approach to modern SQL with plenty of explanations

Not a book but Heinz Klein and Kalle Lyytinen's paper "Towards a New Understanding of Data Modeling" in the Software Development and Reality Construction remains a must-read 30 years later. The organizers of that conference have published a free PDF copy of SDRC if you look around a bit.

Agreed with hyperman and Tomte that C.J. Date is excellent. I would also mention Gray and Reuter, Transaction Processing: Concepts and Techniques.

For fundamental database theory see Hellerstein’s CS 186: Introduction to Database Systems https://youtube.com/playlist?list=PLhMnuBfGeCDPtyC9kUf_hG_Qw...