> > In the case I exposed, what is the recomanded Indexes or Constraints?
>
> Well, given that there is a logical difference between the two,
> choose what fits your requirements.

sorry, may be i explain myself, I ask for the definition of indexes or
constraints to resolve the TWO optimized acces I tell in the first
message...

select coalesce(max(N_Doc),0)+1
from Docs
where N_year=new.N_year
into new.N_Doc;

and

select *
from Docs
where N_year=:N_Year
order by N_Doc;

(both fields are integers)

Tks
Alejandro