I keep as much state as I can in the database, yes. For example - foreign keys. I use constraints in the database to enforce application logic.
I could do this in the backend, yes. But that's needless complexity and it will blow up. Eventually, I'll write something to the database that's inconsistent and then I have to fix it. Because bugs happen.
hmm, i don't want to come across as argumentative, it is more curiosity, because i simply never wrote apps that way. i just don't see how application logic could affect the data itself. the data is independent, and of course there are constraints for data consistency, but it is completely separated from the application logic. application logic doesn't make it into the database at all, or if it does then at best i might store some application specific states in a separate area in the database. effectively a different database than the one that has actual data. i can't think of an example where that separation would not be possible.
I could do this in the backend, yes. But that's needless complexity and it will blow up. Eventually, I'll write something to the database that's inconsistent and then I have to fix it. Because bugs happen.