[dajonker]

Yes, the data model is probably the most important aspect of your application, it defines the relations and constraints. With a good data model, you don't need to write a lot of code to deal with it. Having lots of code that deals with weird situations in the database means your data model needs some serious consideration.

A database in my opinion is not a good place to write business logic with functions and triggers, since there is lack of tooling that would make development and debugging easy. Let the database do what it does well, which is storing and querying data.