Is it possible to define a constraint based on the values in other rows in the current table?

Hi,

I'd like to enforce that in a transaction, after a couple inserts & updates, a particular column has continuous values like 1, 2, 3, and never any gaps. Is it possible to do?

I gave a concrete example here: https://stackoverflow.com/questions/45187113 <https://stackoverflow.com/questions/45187113> didn't get any answers yet.

Am I looking at the wrong direction? Should such feature be implemented with constraints?

Thanks.