Re: object algebra

Neo wrote:

>>>You're confusing missing information and nulls.
>>>RDM creates NULLs when information required by a tuple is missing.
>>
>>Can you illustrate? Which operator(s) create(s) nulls? Are you sure
>>that operator is in the TTM version of the RDM? Which version of the
>>RDM are you assuming - or, if you prefer, whose exposition of the RDM
>>are you using?

> 
> The creation of NULLs in RDM is rooted in its definition of a
> relation.

I've nearly reached the point of not responding, but I'll make one more attempt for good meaasure.

Please can you explain the definition of a relation which you think means that the RDM must create nulls? And can you give a reference to where the version of the RDM you are using or assuming is defined? It doesn't seem to be the same as the version(s) I'm used to.

Your previous answer contained no definition of a relation which explains why nulls are an integral part of the RDM. Nor did it contain a discussion of operators which was what I thought you might think created nulls (it's OK if you don't think any of the operators create nulls - but it would help if you said so).

-- 
Jonathan Leffler                   #include <disclaimer.h>
Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/