[dgb23]

My advice: Yes. Get a good book and a interactive SQL editor. Learn the concepts and try them out. Play, ask questions and try to answer them. Skim over stuff that doesn't interest you at the moment. Write stuff down.

Then after a while you'll encounter new concepts (a new book, an online comment, an interesting tech talk etc.), have new ideas or forget/get rusty on old ones, then you repeat the above.

Continuous learning is part of the job IMO. I did the above several times and will do them several times again in some fashion or another.

For me it has had real value - repeatedly - that I didn't even know existed before I accidentally came across a situation where I could apply some concept I learned this way.

Sure, the first time you apply something "in anger", you will get to the nitty gritty details, which is work but you cannot even recognize an opportunity if you haven't prepared your mind for it and played around with ideas and concepts before - except you have a significant time budget for this kind of thing on the project, or a colleague who can introduce it, but my recommendation is to not rely on that.