I don't think it's good practice to use NULL to mean anything more than "unknown or missing value". Perhaps gis_globe should be "Earth" for Earth? Then there's no ambiguity.
Alan
On Fri, 25 Mar 2005 19:14:00 +0100, Egil Kvaleberg egil@kvaleberg.no wrote:
Egil Kvaleberg wrote:
[...]
where gis_globe is NULL for Earth.
[...]