Tables and Combo Boxes (1 Viewer)

I can never seem to get this right so if someone can kindly direct be to a resource, I would really appreciate it.

What I'm trying to do is:

1. Have a list of cities and a list of communities within each city.
2. When entering a contact, I want to choose a city from the City table and be able to add (on the fly) if a city that I want doesn't exist on the table.
3. In addition, I want to choose a community the contact lives in but only see the communities that exist in the selected city. Again, I want to be able to add a community on the fly if the one sought does not exist.
4. I should not be able to enter a community if the city has not been entered.

I look forward to receiving any help that I can get and extend my thanks in advance.

Thank you.

These operations you do in a form. No access to tables for users. You have cascading comboboxes (search) and the Not In LIst event for a combo, to insert new stuff. Look in the manual.