Huge +1 to Database Design for Mere Mortals. This was the second database book I read (the first was SQL Antipatterns, not a bad book but also not a good first book) and far and away the most helpful. It took me 3 days to read, I had a miserable flu after flying home from a vacation (pre-COVID), and I was still able to follow the author without any issue. I highly suggest a physical copy & writing in the margins, underlining etc, though that's something I do in general so YMMV if you don't get anything out of that.

As far as "technical" books go, it's very nontechnical, and if you're already very experienced & good at normalizing it maybe won't help you THAT much, but for someone who's at all junior, I can't recommend it enough. The biggest takeaway (beyond, "what's a normalized database look like") is to keep questioning the real-life system you're working in & to ask questions of stakeholders who understand it better than you, but me saying that isn't at all doing it enough justice compared to how well the author elaborates on the point. (btw, Data And Reality is also good for this, though a lot more theoretical in approach)

If you're really new to databases you'll want to supplement this with something that does normalization more formally, I don't have a great single suggestion for that. I read two of C.J. Date's books, honestly I found them mind-numbingly tedious to get through but I can't say I didn't learn from them. But...I also can't really recommend them because I was so bored by them that it made me stop reading altogether for like 4 months because I was just putting off finishing these books (LPT: always be in the middle of 2 books at the same time, unfortunately for me, both of my books were these lol). I did also read Art of SQL, it was both enjoyable & interesting, but maybe not what you're looking for if you want something super structured that will take you from point A to point B.

If you weren't aware, Database Design for Mere Mortals 25th Anniversary Edition was released last December!

I had seen that! Do you think it's worth buying & reading the updated version? As much as I loved the original, I'm not sure how much I'd get out of reading a book that's 90% the same content at this point. Though tbf I guess I wouldn't mind just supporting the author so maybe I'll pick up a copy and skim it at least.