SQL queries/statements with special characters in comments (or maybe elsewhere?) will fail in a way that the query does not produce any results. This applies for characters like è, é, ä, ü, etc.

For example:

SELECT Name, Population
FROM Country
-- sélectionner uniquement les pays du continent donné
WHERE Continent = :Continent


Please avoid special characters in SQL statement. Although this looks like it would be a simple fix, it is technically not as trivial as one might think.