A recent experiment with IMF, CIA, and World Bank datasets had me fighting to map ISO 3166 Alpha-3 codes to ISO 3166 Alpha-2 codes. The reason I had to perform the mappings, is because most downloaded flag icon libs on the web are based on Alpha-2 codes.
I have managed to map 183 countries in my local database, and am making the clean CSV available for download here.
The format is:
ISO ALPHA-2 Code , ISO ALPHA-3 Code AF,AFG AX,ALA AL,ALB DZ,DZA