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RE: Primary and Foreign Keys
- From: "Bullard, Claude L (Len)" <email@example.com>
- To: "Thomas B. Passin" <firstname.lastname@example.org>, xml-dev <email@example.com>
- Date: Sun, 22 Jul 2001 13:02:43 -0500
Umm, I can't seem to get my thinking past the need to
be able to say (since I am reverse engineering
backwards from the relational model) that
the value for this is over there. It is almost
as if one needs to denormalize but that seems
wasteful. That is why links look attractive.
It is true, that the task is to enable a way
for them to describe the access and to ensure
that the data model doesn't get in the way of
different people doing that different ways.
That is why the reply to so many requests for
ad hoc querying capabilities is to say "buy
a copy of MS Access or Crystal Reports and
learn to use it with ODBC".
Yes, when collecting data, it can stay in
the relational database and be collected
as XML. So rather than modeling foreign
keys, what may be needed are the kinds of
co-occurrence relationships one can model
as Schematron assertions where values have
to be checked and that is indeed a big part
of the problem I have to solve.
Ekam sat.h, Vipraah bahudhaa vadanti.
Daamyata. Datta. Dayadhvam.h
From: Thomas B. Passin [mailto:firstname.lastname@example.org]
I'm not sure that you have to model foreign keys in xml-schema to deliver
this data. If all these different agencies need to access the data, they
need to know how to make queries and how to interpret the results of the
queries, but they don't necessarily need to know a lot about the data model
or database internals. Maybe all this data can stay in relational databases
while being returned as xml.
To me, the challenge is how to describe the queries so that the user
agencies or applications can figure out how to get what they want. I
wouldn't want to let anyone have full open access to my databases, most
likely. How does this fit in with the task you are asking about?