String agg vs. stuff ordered.sql

-- Original version
SELECT DISTINCT location
	,stuff((
			SELECT ',' + cast(a2.npa AS CHAR(3))
			FROM areacodes a2
			WHERE a2.location = a.location
			order by a2.npa
			FOR XML PATH('')
			), 1, 1, N'') AS areacodes
FROM areacodes a
ORDER BY location;

-- SQL Server 2017 version
SELECT location
	,string_agg(npa, ',') within group (order by npa) AS AreaCodes
FROM areacodes
GROUP BY location
ORDER BY location;