States and Countries

[ExtremeGuy]

I would like to know your opinion:

I have been using PHP and MySQL for a handfull of years now and have created many databases. I am a little confused over which way to save country and state information in tables. I have done it a few different ways and was wondering if there is an unwritten standard that works better than another.

Here are the ways that I have done it in the past with US states:
1) The full state's name (ie. New Hampshire)
2) The state's abbreviation (ie. NH)
3) An id # for the state which is defined in an include file (ie. 28)

So, do most people use one of these methods, and if so which one?

Thanks!

[lazzerous]

I use a mix of all three, so all information is there

create table us_states (
id int(2) uique auto_increment,
state_abbr char(2),
state_name char(17)
);