Re: Does Codd's view of a relational database differ from that of Date & Darwin? [M.Gittens]
Date: Mon, 06 Jun 2005 10:56:59 +0100
Message-ID: <42a41deb$0$8723$ed2619ec_at_ptn-nntp-reader02.plus.net>
mountain man wrote:
> According to this reference we can replace a null in the salary
> field with "Salary not known" and/or "Unsalaried". This has
> taken some work to do, by a database professional, to derive
> an "improved" version of the personnel table (when needed).
>
> So what? The original design schema is simply missing information
> for these elements, and this information needs to be entered,
> and/or determined and entered.
If you replaced both "Salary unknown" and "Unsalaried" with NULLs, how do you distinguish between the two?
> Why should a qualified database professional spend time on
> such a problem when the only real and viable solution to this
> problem is to identify the missing information and then to get
> it into the database?
"Unsalaried" isn't missing information. And it's not always feasible to fill in the gaps.
Paul. Received on Mon Jun 06 2005 - 11:56:59 CEST