Way to do “Any” on an aggregation in SQL Server

I have three fields that are always tied together (is there a proper term for this?), such as:

table

• [other fields]
• country_name (United States)
• country_iso2 (US)
• country_iso3 (USA)

In other words, whenever I have the value of one I have the value of all thre (as if the country would be a FK to another table).

In SQL Server, this would verbosely be done by doing something like:

SELECT country_name, country_iso2, country_iso3 FROM table
GROUP BY country_name, country_iso2, country_iso3

Is there a way where I can only group on one (instead of three) and still get the same values? Something like:

SELECT country_name, country_iso2, country_iso3 FROM table
GROUP BY country_name

Answer

You can use select distinct:

SELECT DISTINCT country_name, country_iso2, country_iso3
FROM table;

This eliminates the need for the GROUP BY.

Alternatively, you can use aggregation:

SELECT country_name, MAX(country_iso2), MAX(country_iso3)
FROM table
GROUP BY country_name

This has the nice property that if any of the ISO codes happen to be NULL, then only the actual value is returned.