Ivan Prenosil wrote:

> (You are talking about rdb$relation_fields and rdb$FIELDS, aren't you?)

Yes.

> It is simple:
>
> This will set null_flag in rdb$fields:
> CREATE DOMAIN D INTEGER NOT NULL;
>
> While this will set null_flag in rdb$relation_fields:
> CREATE TABLE T ( I D NOT NULL);
>
> You can have general domain, that is further restricet at table level, like
> CREATE DOMAIN D_BOOL INTEGER;
> CREATE TABLE TAB (
> A D_BOOL NOT NULL,
> B D_BOOL
> );

I get it. Thanx.

--
Milan Babuskov
http://fbexport.sourceforge.net
http://www.flamerobin.org