Database Structure Modeling Capabilities

Hello,
I have just recently come across the Nette Framework project and its Database component, and it looks quite interesting. I am thinking of using it in a project of mine, but I have some questions before I can start, and would greatly appreciate help:

1. Is it possible to group/model multiple database tables into one “entity/object”? For example, if I have different tables for different product types, but I want to query all of the products, can I create an entity/object called “products” which would actually represent all of the different product tables in my database, and thus have all those tables queried automatically by simply referencing “products” in my code? In this way I can use one command for multiple tables instead of one command for each table. If this is NOT possible, do you know of any similar tools/projects in which this can be done?
2. Can I change my database tables/structure while keeping the same application/php code? For example, if I decide to merge two tables or to split one table into two, do I have to change my application code (for example, do I have to re-create my entities/objects) or can I keep it all the same? I am looking for a solution that allows me to change my database tables/structure without having to change my application code. If the Nette Database tool cannot do this, do you know of any similar tools/projects in which this can be done?

Thank you very much in advance for your kind assistance,
Best Regards,
Michael