> It does exactly what I need... the only problem is that I understand how it
> works, in the same way I undestand the Big Bang!! :) mmhh... I'd love to read
> some article about recursive sql with firebird... any chance you know where I
> can find it? I've tried with the documentation of FB, but couldn't find any
> tutor...

There was my presenttaion at Bergamo Conference about how recursive CTE works.
Ask Fabio about details... Probably it will be allowed to publish it in some near feature.

Also use Google - it could help ;)

Regards,
Vlad