Re: SQL3 UNDER

On Tue, 23 May 2000, Chris Bitmead wrote:
> If you think the semantics are different provide a specific example
> (including SQL) of how you think their behaviour is different - that is
> how you think UNDER should work differently to current INHERIT.
>

I'll try to provide examples later. For now, did you see the gif attachments
on a earlier message of mine? The UNDER and CLONES/INHERITS gif pictures
provide a graphical view of what I mean. UNDER creates tree hierarchy down
vertically, while INHERITS supports multiple inheritance in a lateral
direction. The UNDER trees can be under any table that is part of an INHERITS
relationship. UNDER and INHERITS work at different levels sorta. A subtable
in an UNDER hierarchy can't be in an INHERITS clause because it is logically
just part of its maximal supertable. In other words, INHERITS can provide a
relationship between different whole trees created by UNDER, by way of a
maximal supertable being inherited by another maximal supertable with its own
UNDER tree. Make any sense? :-)

--
Robert B. Easter
reaster(at)comptechnews(dot)com