-- *** before: ***
-- every dialect had its own name for the same aggregate
SELECT GROUP_CONCAT(Name) FROM country GROUP BY Continent;  -- MySQL, SQLite
SELECT string_agg(Name, ', ') FROM country GROUP BY Continent;  -- PostgreSQL
SELECT LIST(Name) FROM country GROUP BY Continent;  -- Firebird

-- *** in version 2016: ***
SELECT
    Continent,
    LISTAGG(Name, ', ') WITHIN GROUP (ORDER BY Name) AS Countries
FROM country
GROUP BY Continent

-- Support: Oracle since 11g Release 2 - and among the seven dialects
-- only Oracle knows the standard name. MS SQL Server 2017 has
-- STRING_AGG(Name, ', ') WITHIN GROUP (ORDER BY Name), the others keep
-- the names shown above, and Access has no such aggregate at all.