Hi,

> could you please expand on this ?
>
> I am afraid I didn't understand.
>
> We start with this database:
>
> create table Stars (
> Star_ID integer not null,
> System_ID integer,
> primary key (Star_ID)
> )
>
> create table Systems (
> System_ID integer not null,
> Planet_ID integer not null,
> primary key (System_ID,Planet_ID)
> )

If your system is identified by SYSTEM_ID alone, why isn't it the Primary
Key then?

From your metadata, rows in table SYSTEMS are identified by SystemID and
PlanetID.

With regards,

Martijn Tonies
InterBase Workbench - the developer tool for InterBase & Firebird
Firebird Workbench - the developer tool for Firebird
Upscene Productions
http://www.upscene.com

"This is an object-oriented system.
If we change anything, the users object."