Re: object algebra
From: Neo <neo55592_at_hotmail.com>
Date: 25 Feb 2004 12:38:36 -0800
Message-ID: <4b45d3ad.0402251238.21db43af_at_posting.google.com>
Date: 25 Feb 2004 12:38:36 -0800
Message-ID: <4b45d3ad.0402251238.21db43af_at_posting.google.com>
> NULL was brought on by the primitive data type system in SQL DBMS',
> not anything intrinsic to the relational model, as I'm sure has been
> explained to you before.
NULLs are not created by SQL.
NULLs are not created by RDM's primitive data type system.
NULLs are caused by a mismatch between RDM's ability to model data in
some applications under some conditions. For example, RDM says to
reality, my tuple MUST have X, Y, Z. Reality says, I can only give you
X and Y. RDM then fills Z with NULL. RDM creates NULLs. Under the same
conditions, TDM/XDb1 does not create a NULL.
Received on Wed Feb 25 2004 - 21:38:36 CET