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Re: Foreign key problem

From: x <x_at_not-exists.org>
Date: Fri, 16 Jun 2006 12:10:46 +0300
Message-ID: <e6tsbe$dps$1@nntp.aioe.org>

"paul c" <toledobythesea_at_oohay.ac> wrote in message news:Szfkg.33274$IK3.15126_at_pd7tw1no...

> If Codd used the word glue I imagine it might have been as a synonym for
> coherence, which I could buy if I knew his context.

Here is the context you asked for:

Chapter 3: Domains as Extended Data Types, page 44. Section 3.2 Nine Practical Reasons for Supporting Domains:

"_First_, full support of the domain concept is the single most important concept in determining whether a given relational database is integrated. Consider the consequences of alleging that a relational database viewed as a collection CD of domains and a collection CR of relations could be split into two databases, without any loss of information or of retrieval capability."

"This first reason for supporting domains can be concisely stated as follows: _domains are the glue that holds a relational database together_. Notice that I said _domains_, not primary keys and foreign keys. The concept of keys in the relational model provides an important additional and specialized kind of glue."

From what I've read so far, the importance of domains is emphasized in several chapters.

> Based on previous visits, one of the two university libraries here
> sucks.

Sorry to hear that.

> I was only having fun with the word - made me think of databases
> held together with post-its, paper clips and binder twine (which some
> probably are), if somebody thinks it's important, maybe there should be
> a thread titled "Where's the glue?"! But maybe that's a better question
> for an OO group!

I suspected that. As you can see, I wasn't. Received on Fri Jun 16 2006 - 04:10:46 CDT

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