In my script (PHP), I use the tz database label for each location in my database: http://en.wikipedia.org/wiki/Tz_database
I am entering a whole series of places (countries, provinces, states, cities, etc.) from around the world, and for each, I have found it very difficult to know which label from the IANA Time Zone Database to use.
Searching the location on wikipedia gives me the time offset (UTC+n) and the timezone abbreviation (EST, etc.) but neither helps in knowing which entry to use in the tz database.
E.g.:
Washington DC uses, as best as I could figure out, 'America/New_york'.
Dallas, TX uses 'America/Chicago' (unless I'm mistaken!)
There is a small African country for which neither its capital city nor its largest city were in the tz database. Which tz entry to use?
There must be a database somewhere, or a resource which clearly links every location on earth (country, state, province, city, etc.) to a specific entry in the tz database. Where can I find it?
One approach you might consider would be to find the latitude and longitude of the location in question.
Then you can look up the applicable time zone for those coordinates using one if the methods described here.