Philippe,
> Is there a way to force the date conversion to fail sliently, and simply
> return a null in case the parameter is not a valid date?
You'd need to write a custom function, using an external language that allows
you to test for valid date values. I prefer using PL/perlU with
Date::Manip, but use what you like.
--
Josh Berkus
Aglio Database Solutions
San Francisco