> Ah, i already noticed that not all Firebird administration tools are
> working with quoted identifiers.

In Firebird you can use quoted and regular identifiers and this is also part
of SQL99 standard (I suspect also SQL92). Identifiers that are not quoted
(i.e. regular identifiers) are equal to the quoted identifiers in upper
case.

> I don't know if i should use setNull(<nbr>, Types.INTEGER) or
> setNull(<nbr>, Types.NULL).

you should use setNull(<nbr>, Types.INTEGER)

Roman