Claudio,

> The setNull isn't useful and if i have the possibility to have null value
> the PreparedStatement isn't useful too.

It is useful, but maybe NOT in a select statement.

But if you do inserts or updates with SQL statements the Param.Clear
method will set the Param to NULL thus setting the inserted/updated
field to NULL.

INSERT INTO MYTABLE ( MY_ID, MY_NAME, MY_OTHERFIELD )
VALUES ( :ID, :MYNAME, :MYOTHERFIELD );

if you do ParamByName ( 'MYOTHERFIELD' ).Clear and execute the statement
the field will contain NULL afterwards.

Luc.