Re: The fable of DEMETRIUS, CONSTRAINTICUS, and AUTOMATICUS

From: Kenneth Downs <firstinit.lastname_at_lastnameplusfam.net>
Date: Tue, 19 Oct 2004 12:25:18 -0400
Message-ID: <e5f3lc.8t6.ln@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 me

Received on Tue Oct 19 2004 - 11:25:18 CDT