I'm building an International Website. Users can choose their country when they sign-up from a `<select></select>` field in a form.

Assuming someone didn't use the form to send the data to the processing page where I validate the data, what is better to do to check if the country is valid, to consult an array or a database of countries? (All the countries in the world)

Programming language: PHP 5.3.5

Database: MySQL 5.0