From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
---|---|
To: | Gregory Stark <stark(at)enterprisedb(dot)com> |
Cc: | Tzahi Fadida <Tzahi(dot)ML(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org, Brandon Aiken <BAiken(at)winemantech(dot)com>, Richard Broersma Jr <rabroersma(at)yahoo(dot)com> |
Subject: | Re: 8.2 contrib. "Full Disjunction" |
Date: | 2007-06-24 09:42:32 |
Message-ID: | 20070624094232.GA7143@svana.org |
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Thread: | |
Lists: | pgsql-general |
On Sat, Jun 23, 2007 at 10:33:49PM +0100, Gregory Stark wrote:
> "Martijn van Oosterhout" <kleptog(at)svana(dot)org> writes:
> > On Fri, Jun 22, 2007 at 07:38:01PM +0300, Tzahi Fadida wrote:
> >> Let me simplify it in lamer terms.
> >> Basically, you have a cycle in your relations schema. i.e.
> >> rel A: att-x, att-y
> >> rel B: att-y, att-z
> >> rel C: att-z, att-x
>
> I'm still lost. I can see how it would be hard to join these together but I'm
> not sure what result I would be after.
Well, the way I understand it is if you had the following data:
rel A
x : y
1 : 2
5 : 6
rel B:
y : z
2 : 3
7 : 8
rel C:
z : x
3 : 1
10 : 9
That the result would be:
x : y : z
1 : 2 : 3
5 : 6 :
: 7 : 8
9 : : 10
Now, I can't off the top of my head think of a schema where you would
need this, but if you have this problem then I don't see the solution
in plain SQL.
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.
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