Hacker News Reader

Check out https://www.pgexercises.com/ . If you like learning by doing, it's a great resource.

"Experienced programmer" can be a hindrance to learning SQL, depending.

You will need to set aside all your imperative, procedural habits. To use SQL effectively you need to think in terms of sets, unions, intersections, and declarative statements.

If you find yourself thinking "row at a time" you might need to stop yourself. It's not always wrong, but a common mistake many programmers make when first learning SQL.

I thought this text adventure approach is a cool way of learning: http://wwwlgis.informatik.uni-kl.de/extra/game/

https://sqlschool.modeanalytics.com/toc/

Khan academy has a great in-browser environment for learning. Unfortunately the lessons are given in a tone that seems to be targeted towards middle-schoolers, so it can feel a bit irritating at times.

What's your unrelated field? In my experience there's a way to shoehorn SQL into any application if you really want to. Sometimes even when you really don't want to.

Further discussion(s): https://hn.algolia.com/?query=learn%20sql