I'm retired, the project I have in mind is for fun and I doubt anyone else will ever use it.
Some 20 years ago I was involved in a project that used a database, and learned both how hard it is and how important it is to define your, um, framework? correctly. By that I mean the various tables and how they interact. The 2 things I remember that you shouldn't store a datum in more than 1 table, and we ended up with 2-3 "invisible" tables that the user never saw but were needed to ensure each datum ended up in a single table. My app will have 5-7 tables.
Where is a good place to learn how to design this? And what is it called?
Second, my application (it's for a game) has 5 players, each playing 3 positions. You do not know which player is playing which positions. Each position has a name. Say we have a, b, c, d, e, f, g, h, .... I'm playing a, b, and c. Fred could be playing d, g, and n. But I don't know that, I have to deduce it. How would you suggest I store this in a database?
Finally, this will run on a laptop. Which database system should I use (donning asbestos underpants)?
Oh yeah, I'll be writing this in either Java or Kotlin.