Re: Database design, Keys and some other things
From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Sat, 01 Oct 2005 16:08:32 +0200
Message-ID: <433e97b0$0$11075$e4fe514c_at_news.xs4all.nl>
>
> Agreed. This is an important difference.
>
> Perhaps the difference is between "externally supplied data" and "internally
> generated data". In a typical personnel system, new employee ids are
> assigned by the HR department, and they are responsible, ultimately, for
> avoiding duplicate assignments. The IT department ultimately is only a
> custodian of data that the HR department "owns". Of course, the IT
> department codes duplicate rejection somewhere into their systems, so as to
> help HR discover their errors in a timely fashion.
>
> So, when we have a "surrogate key in the database at hand" (or, if you can
> accept it, "in the system at hand") what we have is data that is "owned" by
> the system itself, rather than merely kept in custody by the system for its
> owners.
Date: Sat, 01 Oct 2005 16:08:32 +0200
Message-ID: <433e97b0$0$11075$e4fe514c_at_news.xs4all.nl>
David Cressey wrote:
> mAsterdam wrote:
>
>>There is an important difference. Unless we are talking about >>that specific "*some*" database, the VIN is /not/ a surrogate key in >>the database at hand.
>
> Agreed. This is an important difference.
>
> Perhaps the difference is between "externally supplied data" and "internally
> generated data". In a typical personnel system, new employee ids are
> assigned by the HR department, and they are responsible, ultimately, for
> avoiding duplicate assignments. The IT department ultimately is only a
> custodian of data that the HR department "owns". Of course, the IT
> department codes duplicate rejection somewhere into their systems, so as to
> help HR discover their errors in a timely fashion.
>
> So, when we have a "surrogate key in the database at hand" (or, if you can
> accept it, "in the system at hand") what we have is data that is "owned" by
> the system itself, rather than merely kept in custody by the system for its
> owners.
Makes sense to me. Along these lines:
Exposing system owned data to users should
be done only when necessary:
error codes/messages, hm... what more?
Received on Sat Oct 01 2005 - 16:08:32 CEST