What does define the default category of a product in database?

[borro]

Hello!

If there are two categories defined for the product, what does define the default category of a product at database level?
Is there any way to define the priority(default) category for the product among the others assigned? I'm talking about that category which participate in a product url construction which you can see after seeking some product in a default VM search module

VM3.0.9