Hi,

> > Changing from NULL -> NOT NULL or back is
> > done via a system table update.
> >
> > Exactly why can't you do this? Do you get an
> > error of some sort?
> >
>
> Sorry I haven't explained properly the situation.
>
> The metadata update returns Ok, the structure of the table shows the
> change, but I still can't insert (ou update) that column to NULL. It
> seems that there is was a commit missing, but I commited everything
> (as far I know ;)
>
> The FB returns an error about existing restrintion on that column ***
> null ***.

Disconnect (all connections) and reconnect. I bet it's an internal
Firebird metadata cache thingy.

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server.
Upscene Productions
http://www.upscene.com