Take a look at the "Relational Design Theory"[1] mini-course on Stanford/Lagunitas. Though I had used SQL for years, I took it as part of the early MOOC on databases that was offered in 2011. It is likely to match up with the intuition you already have about what works well in practice, but it can still be a challenge and rewarding to formalize your intuition and understanding.

The way the course is broken up now, you may need some of the other sections [2] like Intro to Relational Databases or Relational Algebra as prerequisites, since I do not remember if it used SQL syntax.

[1] https://lagunita.stanford.edu/courses/DB/RD/SelfPaced/about

[2] https://lagunita.stanford.edu/courses/DB/2014/SelfPaced/abou...