How to concatenate Distinct values of a single Column in one row?

Question

I have a table with single column Countries as:

Countries

USA
USA
France
India
USA
Russia
France
India

I want to concatenate distinct values in a single row like

Countries

USA,France,India,Russia

How do I write SQL query to achieve the same?

Thanks in advance.

Answer 1

If its from a table Country and fieldName is CountryName, then below query would do good, SELECT STRING_AGG(CountryName) FROM (SELECT DISTINCT CountryName FROM Country) . Incase if you are using older version of SQL, STUFF can be used to achieve the output.

Answer 2

WITH CTE(COUNTRY)AS
(
  SELECT 'USA' UNION ALL
  SELECT'USA'UNION ALL
  SELECT'France'UNION ALL
  SELECT'India'UNION ALL
  SELECT'USA'UNION ALL
  SELECT'Russia'UNION ALL
  SELECT'France'UNION ALL
  SELECT'India'
)
SELECT STRING_AGG(C.COUNTRY,',')
FROM 
(
   SELECT DISTINCT COUNTRY FROM CTE
)C