Re: Primary and Foreign Keys

["Thomas B. Passin" <tpassin@home.com>]

[Bullard, Len]

>
> Consider a design in which the schema represents
> the data-centric approach and should be
> agnostic about what database implementation
> is used.  In other words, it starts out life
> as a relational database (really a hybrid
> because of the GUI layer with business logic,
> so a mid 90s design), then one wants to make
> the data available to different systems at
> different scales (big agencies, little agencies,
> tweeny agencies, sometimes using desktop
> interfaces, sometime handhelds).   That is
> where many of us are today.  We need to
> open our dbs up to different services and
> migrate the push models of delivery to
> pull models in the sense that most large
> reporting systems collate and send their
> data up to collection agencies that then
> regularize them and send them on to a central
> collection agency, like mountain, to stream
> to river to ocean with a data-centric schema
> as the cohesive force.
>

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?

Cheers,

Tom P