I am presented with a dilemma while trying to re-designing the class structure for my PHP/MySQL application to make it more elegant and conform it to the SOLID principle.

The problem goes like this:

Let as assume, there is an abstract class called person which has certain properties to define a generic person, such as name, age, date of birth etc.

There are two classes, student, and teacher, that implements this abstract class. They add their own unique properties to it.

I have designed all the three classes to include all the operational logic (details of which are not relevant in context of the question).

Now, I need to create views/reports/data grids which contain details from multiple classes, for example, say, a list of all students doing projects in Chemistry mentored by a teacher whose name is the parameter to the query.

This is just one example of a view, there are many different views in the application, which uses data from 3-4 tables, and each of them have multiple input parameters to generate them.

Considering this particular example, I have written the relevant query using JOIN and the results are as expected and proper, now here is the dilemma:

Keeping in mind the single responsibility principle, where should I keep this query? It does not belong to either Student class, or Teacher class or any other classes currently present.

a) Should I create a new class, say dataView class, and design it as a MVC pattern and keep the query there? What about the other views? how do they fit in this architecture?

b) Should I not keep the query in code at all, and make it DB View ?

c) Am I completely wrong in the approach? If so what is the right approach?

My considerations are as follows:

a) should be easy to add new views later on if requirement comes, without having to copy-paste-modify code b) would like to make it as loosely coupled as possible so that if minor db structure changes happen, it does not break

I did google searches on report design and OOP report generators, but all the result seem to focus on the visual design of the report rather than fetching the data. I have already taken care of the visual aspect of the report using MVC with html templates.

I am sure this is a very fundamental problem with known solution, but I am somehow not able to find it (maybe searching with wrong keyword). Any nudge in the right direction would be appreciated.

Thanks.