How to change category/products SQL queries?

[OriyanJ]

I'm trying to figure out how can I temper with the SQL queries that affect category/products display.
In case I only want to show certain products with my desired queries (such as showing products with only images or children), where should I be looking?
I'm not asking for coding, only for directions, there I believe I can manage on my own.

In case you're interested of what I'm trying to achieve -
I want to only show products that have children, with future available dates. In case a product have children that are all in the past, it will not be shown.

[GJC Web Design]

the vm admin model products.php

[OriyanJ]

Thank you!