Re: Database design/normal form conundrum

From: robert <gnuoytr_at_rcn.com>
Date: 27 Mar 2004 11:04:15 -0800
Message-ID: <da3c2186.0403271104.3ab4da6e_at_posting.google.com>


cartermark46_at_ukmail.com (Mark Carter) wrote in message news:<d3c9c04.0403260239.20a57d3f_at_posting.google.com>...
> Normally, in one-to-many relationships, where you don't know how many
> is many, it is necessary to have two tables linked to each other. But
> supposing there were a fixed number of relationships. How would that
> change your view over using two linked tables over one big wide one?
>
> Here's the setup:
>
> A database exists whereby each record contains a data value. The data
> value has exactly five tests applied to it. A test consists of a
> pass/fail result, a user comment about the failure, and a user
> decision as to whether or not to ignore the error.
>
> So, that's five tests, consisting of 3 fields apiece, making 15 fields
> in all; and there is possibility that a couple more tests may need to
> be added.
>
> So which is better:
> 1. just have one table with lots of fields
> 2. two tables with much fewer fields, but with all the complications
> that linking implies

the one complication that *always* needs to be considered is the projection-join anomaly. it's the one thing that is guaranteed to muck
up a design; and the real reason (although many practitioners don't quite
know why they do what they do) that single table never-normalized systems
get built. "with all the data to hand, i can code my way out of any corner i paint myself into". and will. frequently. Received on Sat Mar 27 2004 - 20:04:15 CET

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