Re: One-To-One Relationships
Date: Tue, 4 Dec 2007 12:55:30 -0800 (PST)
Message-ID: <78acb467-3d08-4530-afb5-f01cba4410b2_at_b40g2000prf.googlegroups.com>
On Dec 3, 6:01 am, Jan Hidders <hidd..._at_gmail.com> wrote:
> On 2 dec, 18:53, vldm10 <vld..._at_yahoo.com> wrote:
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> > On Dec 2, 4:36 am, Jan Hidders <hidd..._at_gmail.com> wrote:
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> > > On 1 dec, 06:26, vldm10 <vld..._at_yahoo.com> wrote:
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> > > > On Nov 30, 9:34 am, Jan Hidders <hidd..._at_gmail.com> wrote:
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> > > > > Why by only one attribute? Why not by a set of attributes? Or a
> > > > > combination of attributes and relationships (as is the case for weak
> > > > > entities)?
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> > > > This is OK, but my advice to you -don't use it often.
> > > > I will give you one example:
> > > > The relation has A1, A2, A3, A4 "attributes" and they are mutually
> > > > independent (i.e. they are in BCNF)
> > > > The "attributes" can change their values for "entity" like in
> > > > "temporal DB". User needs on line all information for any "entity" in
> > > > any moment.
> > > > Can you please write the key for this relation so that we can discuss
> > > > it.
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> > > You do realize we were talking about ER modeling, not RM modeling,
> > > don't you?
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> > > -- Jan Hidders
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> > Here in this tread it is about E/R and RM as well as relationship
> > among them and I also used terms "entity" and "attribute".
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> My remark that you responded to was only about ER modelling.
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> -- Jan Hidders- Hide quoted text -
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> - Show quoted text -
Vladimir Odrljin Received on Tue Dec 04 2007 - 21:55:30 CET