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Re: Domain

From: Dawn M. Wolthuis <dwolt_at_tincat-group.com>
Date: Mon, 29 Dec 2003 22:30:56 -0600
Message-ID: <bsqv24$r4r$1@news.netins.net>


"Joe "Nuke Me Xemu" Foster" <joe_at_bftsi0.UUCP> wrote in message news:1072725369.339410_at_news-1.nethere.net...
> "Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message
<news:bspsmq$eqo$1_at_news.netins.net>...
>
> > "Joe "Nuke Me Xemu" Foster" <joe_at_bftsi0.UUCP> wrote in message
> > news:1072722607.119541_at_news-1.nethere.net...
> > > "portroe" <bob_at_sleigh.com> wrote in message
> > <news:bspj1d$m3r$01$1_at_news.t-online.com>...
> > >
> > > > can anybody give me a definition of domain as applied to DB theory,
> > >
> > > If a DBMS had proper support for defining types, domains would be
types.
> > > Just as most modern programming languages support the creation of new
> > > types, RDBMS' should support the creation and use of new domains.
>
> > I agree except that I would state it more like "DBMS's should use modern
> > programming languages where classes define types aka domains"
>
> Oh no, you're a Pure OOPie-head as well?? =^|

Why thank-you -- but I'm only 99.8% "Pure" ;-) As for Java or other OO languages, I like them to the extent that they get the job done. I'm comfortable with non-OO languages as well and just as with my angle on relational databases, I tend to look at various technologies in terms of pros and cons. I don't take on a religious zeal for any technology abstractly -- I'm inclined to favor what works in practice. Java works even though it is not perfect. SQL works and it falls well below perfect to the point where I really dislike the language. I'd rather we start with Java than SQL for defining types since what we need seems to be pretty much there already.

> > To answer the original question, without looking up anyone else's
> > definition, I'd say that a domain is a named set of possible attribute
> > values for a specified attribute.
>
> That sounds more like a "field" with a "validation rule" to me...

I wrote it from a mathematics background, adding in the fact that the set must be named in relational databases where it need not be in mathematics. I know it is not always how folks perceive domains, but all it really is is just a set that limits the possible values for an attribute, right? Beware of anyone who adds in words like "atomic" into definitions of "domain". Unless we (as a profession) can find a useful definition of atomic, I'd like to leave such useless jargon out of database discussions altogether.

--dawn

> --
> Joe Foster <mailto:jlfoster%40znet.com> "Regged" again?
<http://www.xenu.net/>
> WARNING: I cannot be held responsible for the above They're
coming to
> because my cats have apparently learned to type. take me away,
ha ha!
>
>
Received on Mon Dec 29 2003 - 22:30:56 CST

Original text of this message

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