Re: The fable of DEMETRIUS, CONSTRAINTICUS, and AUTOMATICUS
Date: Tue, 19 Oct 2004 12:25:18 -0400
Message-ID: <e5f3lc.8t6.ln_at_mercury.downsfam.net>
Marshall Spight wrote:
> "Tony Andrews" <andrewst_at_onetel.com> wrote in message
> news:1098201951.251759.85460_at_z14g2000cwz.googlegroups.com...
>> Marshall Spight wrote:
>> >
>> > This was roughly my thought as well. The *best* way to enforce
>> > a constraint is structurally, so that in the language of the
>> application's
>> > schema, it is *not possible to express* corrupt data.
>>
>> That's great when possible. But some constraints just aren't
>> expressible structurally - examples given in earlier posts.
>
> Agreed.
>
>
>> For those, >> what you want is a complex declarative constraint (aka an "assertion") >> - something many DBMSs can't do, unfortunately.
>
> Yes, that's exactly what you want!
>
>
> Marshall
I have just made a post where I show how to handle all of Tony's examples structurally. Can you think of any that are even tougher? I would be happy for the exercise in finding the limits of my hypothesis.
-- Kenneth Downs Use first initial plus last name at last name plus literal "fam.net" to email meReceived on Tue Oct 19 2004 - 18:25:18 CEST