Sorry if this was asked elsewhere, but I could not find a clear answer anywhere.

I decided to start learning to use relational databases a little more, namely SQL. This is a basic question for beginners, but it is probably necessary to get started.

Basically, I was a bit confused about the best practice of using SQL (or another). In college, I got access to databases (using JSON strings) for things like mobile applications, but I never designed or built the database myself, as my teacher made the database available to us.

Suppose I have a C # application that contains genealogy information (i.e. families and their members), and I wanted to save each person in a database. Will I just use a structure that I already have, but save in the fields in the database instead of an XML document or a text document? Or it works differently i.e. I create a database with required fields, and then simply extract it from the database in the aC # application and manipulate the data as I see fit, so the application will be completely different (therefore, the C # application basically does not actually hold / not store any data and just works on what is being fed from the database)?

What bothers me is that usually when I store my C # objects in a dictionary or list, for example, instead, I just get directly from the database? or extract from and store data in a normal structure and work from there (perhaps this will lead to the victory over the quick search point from the database)?

I can think a little. Hope this makes sense. thanks in advance