Re: database integrity

"erk" <eric.kaun_at_gmail.com> wrote:

> A DBMS can't protect the data unless it knows what constraints to
> enforce. Falsehood isn't enforceable in general, although specific
> variants might be - for example, aging could be, although it raises the
> issue of whether the fact that something was ONCE true, but no longer
> is, matters - and when it became invalid, of course.

I believe this may definitely be an issue with specific elements of data -- ie: that data can be NO_LONGER_TRUE as a result of change, during the passage of time.

Perhaps an example of this is where data values are calculated on the basis of rules, themselves reflecting current legislation.

When legislation changes, the rules may need changing, and thus the issue of the previous (retrospective) data values may need to be addressed --- and sometimes into minute detail, depending on the complexity of the schema.

> To me, aging falls into the category of integrity constraints over the
> system catalog, which is implemented... well, nowhere I know of.

When you say "aging" what specifically do you mean? Can you provide a concrete example?

Many thanks,

Pete Brown
Falls Creek
Oz
www.mountainman.com.au Received on Sat May 21 2005 - 08:33:20 CEST