Re: Data independence

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"Alfredo Novoa" <alfredo_at_ncs.es> wrote in message news:40a34518.331576_at_news-read3.maxwell.syr.edu...
> On Thu, 13 May 2004 11:46:22 +0300, "x" <x-false_at_yahoo.com> wrote:
>
> >
> >
> >
> >> It is possible to write applications that are independent of
> >> the change of key constraints in a RDBMS ?
> >
> It does not make sense to me.
>

Suppose you have an application that use some relvars like this:   R(A1,A2,A3,A4,B1,B2,B3,...)
where {A1,A2,A3} is a candidate key for R. After some time you find out that {A1,A2,A3,A4} is the "real" candidate key for R.
Do you need to modify the application ?
There is a way of writing applications that are not affected by this change ?

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