Multiple levels of tagging? Dynamic tags? What's the solution?

I am trying to come up with an efficient way to be able to group companies by Region, then by Country according to the region, and finally by City according to the country. Since a company could have an office in more than one region,country and city I think that a setup with tags could work, where I would have a tag set for each region, country and city (3 independent tag sets).

Now it gets tricky. How do I get the tags to relate to each other? For example, how do I get Paris to be related to France and then to Europe? And then if a company has multiple regions, countries and cities how to associate a particular region with the correct country and so forth. SO if I have the Europe and South America tags for regions, then France and Columbia for countries and then Paris and Bogota for cities how do I relate one tag with it’s corresponding tags?

I am not sure if I am making any sense, it is getting confusing for me to follow myself so explaining it is even more confusing

It made me dizzy too and it’s been a long day, but maybe my rambling will give you something to grab onto.

I see a minimum of three tables:


Company
ID, Name, address, phone, etc.

e.g.
1, IBM, etc. etc.
2, Apple, etc. etc.

City
ID, Name, Region, Country

e.g.
1, Paris, France, Europe
2, Chicago, USA, North America


City-Company
ID, CityID, CompanyID

e.g.
1, paris, IBM
2. bogota, Apple
3. New York, IBM
4. New York, Apple

You can get all the cities of a company from the city-company table, then get the region and/or country from the city table.

Going the other way, you can get all the cities in a region or country from the city table, then get all the companies in that region or country from the city-company table.

I think it would be more correct to also have a region table and a country table which each contained two fields: ID and Name and then use the two ID’s in the city table but I don’t think it’s necessary. If you did, though, all your tags would be ID numbers which would probably speed things up.

I hope this makes at least some sense.

Bob