| From: | hubert depesz lubaczewski <depesz(at)depesz(dot)com> |
|---|---|
| To: | Alexander Pyhalov <alp(at)rsu(dot)ru> |
| Cc: | Achilleas Mantzios <achill(at)matrix(dot)gatewaynet(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: I don't understand something... |
| Date: | 2011-10-03 08:02:16 |
| Message-ID: | 20111003080216.GC4824@depesz.com |
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| Thread: | |
| Lists: | pgsql-general |
On Mon, Oct 03, 2011 at 11:48:45AM +0400, Alexander Pyhalov wrote:
> On 10/03/2011 11:19, Achilleas Mantzios wrote:
> >Alexander, that's a classic one,
> >rewrite your last query as :
> >
> >SELECT count(employee_id) from employees where employee_id not in
> > (select manager_id from employees WHERE manager_id IS NOT NULL);
> >
> >NULLS semantics are sometimes not so obvious.
>
> Thanks.
> It's confusing, that IN check works as expected, but NOT IN works
> this way...
If I might plug:
http://www.depesz.com/index.php/2008/08/13/nulls-vs-not-in/
Best regards,
depesz
--
The best thing about modern society is how easy it is to avoid contact with it.
http://depesz.com/
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