Use The Referencing Clause

If we want we can use the referencing clause to specify a different name [similar to alias name] for :old and :new correlation names.  This is the syntax:

referencing [old as old_name] [new as new_name]

Example:

Create or replace triggergenerateprofID

before insert on professor

referencing new as new_prof

for each row

begin

if :new_prof.pid is null then

select profids.nextval into :new_prof.pid from dual;

end if;

end triggergenerateprofID;