""Dimitar Selensky"" <selensky@...> wrote in message
news:002101c13ecc$cfc43f40$2325a9d5@sel...

> Is there a way to tell that a certain parameter passed to an UDF function

is null?

Yes, use ancient, almost-forgotten, powerful descriptors. They carry the
same info that the engine uses internally.

> I need a function like NVL(<field>, <value>) which will return <value> if

<field> is null and <field> itself if it isn't null...

iNvl and sNvl are examples that have been implemented in the FBUDF.
Caveat: the source code will work only on Firebird once it's compiled. The
SQL script that defines the functions will work only on Firebird, too.

C.
--
Claudio Valderrama C. - http://www.cvalde.com - http://www.firebirdSql.org
Independent developer
Owner of the Interbase® WebRing