On Sat, Jun 23, 2007 at 10:33:49PM +0100, Gregory Stark wrote:
> "Martijn van Oosterhout" <kleptog@svana.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@svana.org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.
