Don’t do:

SELECT first_name, last_name
FROM employees 
WHERE  rownum = 1
ORDER BY creation_date DESC

You probably want to do this instead:

SELECT * from (
 SELECT first_name, last_name
 FROM employees 
 ORDER BY creation_date DESC
) where rownum = 1 

The first query takes the first row returned by Oracle and orders it by creation_date.
The second query gets the first row of the sub-query that contains the sorted records.
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