Ecto and NOT NULL constraint (beginner question)

I don’t know that “just reading” these books can really help anyone but fortunately they are set up to have you working through code. I’ve been using the “Programming Ecto” playground script and music_db in various topics for demonstration purposes (I went through B1.0 Chapters1-7 back in June).

Of all the pragprog Elixir books I’d rate Metaprogramming Elixir as the most challenging one - so that one is likely best enjoyed in small doses (Don’t Write Macros But Do Learn How They Work).

any opinion on Functional Web Development with Elixir, OTP, and Phoenix,

I worked through the chapters that were available before the rewrite. I recommend it for getting more into the “thinking in processes” mindset and would definitiely tackle it before Metaprogramming Elixir.