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Re: Foreign key problem

From: Jay Dee <ais01479_at_aeneas.net>
Date: Thu, 15 Jun 2006 18:09:25 GMT
Message-ID: <pnhkg.65506$YI5.8141@tornado.ohiordc.rr.com>


x wrote:
> "Jay Dee" <ais01479_at_aeneas.net> wrote in message
> news:svbkg.68231$P2.43250_at_tornado.ohiordc.rr.com...
>

>>Hmm.  A _name_ /would/ be necessary to permit your example..

>
> I know. But it shouldn't be.
>
>>But what is the meaning of the overlapping constraints
>>with different names?

>
> Overlapping as in the example, or overlapping as identical ?

As in the example. I interpreted the 'foreign_keys(...)' stanzas to be some sort of expressions of some sort of super constraint in which two of three referring columns had the same referents. What are those expressions? I don't know. What are super constraints? I don't know.

Did you have any specific reason for re-specifying those?

> How about this:
>
> t1(a,b)
> t2(c,d)
>
> (a,b) references (c,d)
> (b,a) references (c,d)

Funky. But fine by me.

not(cardinality(t1) > cardinality(t2{c} intersect t2{d})), right? Received on Thu Jun 15 2006 - 13:09:25 CDT

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