Re: I think my book may be wrong about cardinality, but I'm not sure
Date: Wed, 25 Jul 2007 12:33:14 GMT
Message-ID: <eqHpi.11862$zy4.2170_at_trndny07>
"JOG" <jog_at_cs.nott.ac.uk> wrote in message
news:1185356728.061458.239150_at_g4g2000hsf.googlegroups.com...
> A relationship is a row in a table. Nothing more, nothing less.
I disagree.
Unfortunately, the word "relationship" is used in both E-R modeling and
Relational Data modeling. These two usages have a lot of overlap, but they
are not exactly the same concept.
A relationship in E-R modeling is NOT a row in a table. It's an association
asserted to exist between 2 or more entities, in the real world that the
database describes.
In relational modeling, your comment is correct.
People who see the world exclusively through the lens of the relational data
The association would exist, even if there were no database in which to
record it.