Re: *Proper* solution for 1..* relationship?

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От Wolfgang Keller
Тема Re: *Proper* solution for 1..* relationship?
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Msg-id 20130502172633.225251081660b9ade4124895@gmx.net
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Ответ на Re: *Proper* solution for 1..* relationship?  (David Johnston <polobo@yahoo.com>)
Ответы Re: *Proper* solution for 1..* relationship?  (Richard Broersma <richard.broersma@gmail.com>)
Re: *Proper* solution for 1..* relationship?  (David Johnston <polobo@yahoo.com>)
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> > What still astounds me is that, again, this (correct implementation
> > of 1..n relationships with n>0) is an absolutely standard issue
> > that is as old as relational databases per se and NO ONE has
> > implemented (and documented and tested and...) a standard solution
> > yet?
>
> I would imagine most people are content using a 0..* cardinality
> instead of a 1..*.

Then they don't seem to care for reality. Which is *the* diagnostic
criterion for what psychiatrists call a "psychosis".

Cardinalities, like most aspects of data models, are imposed by
reality (ever happened to have heard of that concept?). If the data
model doesn't match reality, this will be very expensive for someone,
sooner or later.

That this "someone" who in the end has to bear the consequences is
usually not the "database administrator" or "IT manager" etc. is
obvious, unfortunately.

> Please, someone espouse the practical benefits of enforcing that one
> record exists on the child table in order for a record to be present
> on the parent.

In case of e.g. medical information systems, or in my case, maintenance
information systems, quite a few people's lives could depend on the
integrity of the data in the database. A correct data model is one
necessary prerequisite for data integrity.

Is that not enough of an incentive, to not practise homicide (murder?)
by pure lazyness/ignorance/incompetence?

Sincerely,

Wolfgang

P.S.: I would have expected people with such an obscene attitude ("why
care for data correctness") on a list for Access or similar crapware,
but not on a list for PostgreSQL.



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