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Re: Implementing complicated constraints

From: Brian Dick <bdick_at_cox.net>
Date: Wed, 29 Sep 2004 16:47:29 -0400
Message-ID: <jdtzxo8yz9ui$.fvz7df6zphej$.dlg@40tude.net>


On 29 Sep 2004 10:21:38 -0700, Tony Andrews wrote:

> Brian Dick wrote:

>> On 28 Sep 2004 08:11:44 -0700, Tony Andrews wrote:
>>> Of course, having the CID in the A table is a viable work-around,

> but
>>> that doesn't mean there was a relational design flaw before.
>>
>> You need to brush up on your normalization rules. Rule 3 states that
>> columns must be dependent on nothing but the key. Your ATXT column is

> not
>> solely dependent on AID, so your design is not normalized.

>
> Wrong. ATXT is solely dependent on AID, it cannot be determined from
> CID. But there is an additional constraint that ATXT must be unique
> w.r.t. the CID for some reason. If you still think I'm wrong, then
> please show the NORMALIZED database design that resolves the issue.
> Not that it was MY column or design anyway!

Mark C. Stock gave you a possibility. Although, his model implies that A is dependent on B is dependent on C. Is A.BID or B.CID nullable? If so, then Mark's model is not correct either. Need more info about the problem. Received on Wed Sep 29 2004 - 15:47:29 CDT

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