Re: object algebra
Date: Thu, 26 Feb 2004 03:47:29 GMT
Message-ID: <l%d%b.123378$uV3.633352_at_attbi_s51>
"Neo" <neo55592_at_hotmail.com> wrote in message news: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.
Nulls in SQL are the result of a design decision made by the inventors of SQL. They (wrongly, IMHO) thought that 3VL would be a better way of handling missing information than having a separate table with just a foreign key and the optional info.
It is certainly possible to make a different decision in designing future DBMSs.
Marshall Received on Thu Feb 26 2004 - 04:47:29 CET