This is definitely difficult material if you don’t have a background in C programming. Don’t give up the fight.
Answers to your first two questions; I’ll leave the third for the moment because it’s much broader.
Unsigned int(eger)s are whole-number values which cannot be negative.
So: 0, 1, 2, 3, etc.
They are represented differently inside the computer than integers which can be negative. An int is always signed unless you add the unsigned keyword.
A “to-many relationship” indicates a relationship from one object to 0 or more other objects. Specifically, an employee may have any number of assets.
Typically you’ll see references in software and database design to “one to many”, “one to one”, “many to one”, or “many to many” relationships. An employee conceptually has a “one to one” relationship with an employee ID, for example, although typically you don’t describe it that way because the employee ID does not reside in a different object.
Examples of the different types of relationships:
- One to one: US citizen to social security number
- One to many: manager to underling
- Many to one: Vehicles to manufacturer
- Many to many: children to parents (a parent may have multiple children, and a child hopefully has multiple parents)
Don’t get confused between many to one and many to many: yes, there are many cars and many manufacturers, but each car is made by only one manufacturer.
And zero counts as “many”, typically: a manager may not actually have anyone reporting to him/her, but still be a manager.
I think it’s safe to say that some vehicles are designed by multiple manufacturers but still built by just one, but that just illustrates my next point: it’s sometimes dangerous (but usually necessary) to make assumptions about the nature of these relationships. Data errors and software bugs can often be traced back to simplifying assumptions that prove to be incorrect. People do, in fact, have multiple social security numbers on very rare occasion.
(Edit: multiple SSNs are not so rare, apparently, but not legal either.)