Re: exclusive OR possible within a where clause?

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От Ken Tanzer
Тема Re: exclusive OR possible within a where clause?
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Msg-id CAD3a31XrnhARSRAydokSUc_U=Ar9EC=QxRNP6+PtsskT4pqQRw@mail.gmail.com
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Ответ на Re: exclusive OR possible within a where clause?  (David Salisbury <salisbury@globe.gov>)
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If you don't care about which row you get, how about adding a "LIMIT 1" to your query?  Don't know if that counts as "messy" or not... :)

On Mon, Oct 17, 2011 at 12:15 PM, David Salisbury <salisbury@globe.gov> wrote:


On 10/14/11 10:58 AM, David Fetter wrote:
On Thu, Oct 13, 2011 at 07:49:59PM -0400, Tom Lane wrote:
David Salisbury<salisbury@globe.gov>  writes:

Short version, is there a way to implement an exclusive OR in a where clause?

The boolean<>  operator will do the trick.

       (x = y)<>  (a = b)

                       regards, tom lane

Factoring in NULLable columns, that's:

(x IS NOT DISTINCT FROM y)<>  (a IS NOT DISTINCT FROM b)

Cheers,
David.

Thanks for the replies!

I should note ( for the mail list archives I guess )
that the above suggestions don't work.  Both rows are
returned whether I use OR or <>, though maybe I'm not
understanding something.  I'm not sure why <> would work either,
as all I can find is <> is the same as !=, which is
different than the fabled XOR I was hoping for.  In fact
they would never equal.

But in the end it looks like wrapper sql around my output using
"select distinct.." should do the trick.

-Dave


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