"Vilson farias" <vilson.farias@digitro.com.br> writes:
> Let's suppose I can't use sequences (it seams impossible but my boss
> doesn't like specific database features like this one).
If sequences could be effectively replaced by standard SQL operations,
we would not have bothered to invent them. Nor would other databases
have bothered to invent their comparable features (autoincrement in
MySQL, etc). Your boss has got his head screwed on backwards on this
point --- writing a sequence replacement will not work well, and will
not be markedly more portable to other databases.
regards, tom lane