Re: Proposal: 6NF

From: J M Davitt <jdavitt_at_aeneas.net>
Date: Thu, 05 Oct 2006 22:16:05 GMT
Message-ID: <FufVg.4131$Cq3.3594@tornado.ohiordc.rr.com>

David Cressey wrote:
> "David Cressey" <dcressey_at_verizon.net> wrote in message
> news:F4uTg.998$rH1.633_at_trndny05...
>

>>First, let's find out where we all agree,  then work our way towards where
>>there are different viewpoints.
>>
>>Here's a starter:  A schema in DKNF will have no nullable columns.
>>

>
> I got no answers to the first point, but I think we all agree.

(I guess my contribution was lost in the ether.)

>
> Here's the next point.
>
> An outer join between two relational tables will, in general, produce a
> table with nullable columns.

Wait a minute: what does OUTER JOIN have to do with relational theory? Sure, SQL offers an OUTER JOIN, but...

There are *lots* of things I don't like about "outer join between two relational tables:"
- "outer" join

What's outer about a join?
- join "between"

"On" or "of," sure; but "between?" Seems strange. - "relational tables"

Relations or tables: they're different. Pick one. - "in general"

Very vague.
- "[A] table with nullable columns..."

...is not a relation.

> Note: Brian Selzer has carried this point further in another subthread.

Yes, he has. Received on Thu Oct 05 2006 - 17:16:05 CDT