Re: difference nested select union
Bryan,
You may be relieved in knowing that the original poster was
referring to b.id being null in the second query, rather than a.id in
the first! :-)
HTH,
Marco
________________________________________________________________________
____
rem radioterapia, which I immeritately manage, seldom agrees with what
I say
marco greco (Catania, Italy) Work:
marcog@ctonline.it rem radioterapia 39 95 447828 fax
446558
(was mar.greco@agora.stm.it) Achea 39 95 503117
--- On 7 Oct 1996 21:48:59 +1000 Bryan Tonnet <batonnet@zeta.org.au>
wrote:
In <5335hr$i08@nic.global-one.no> Nils.Myklebust@idg.no (Nils
Myklebust) writes:
>Bryan Tonnet <wgtonb@sydsun.itsyd.bhp.com.au> wrote:
>:Jason Wickline wrote:
>:>
>:> I am unsure why I am getting different results from the following:
>:> select id
>:> from a
>:> where id not in (select id
>:> from b)
>:>
>:> and
>:> select a.id, b.id name
>:> from a, outer b
>:> where a.id = b.id
>:>
>You forgot to include the key sentence:
>:the count of the null name is not equal to the count of id in first
>:sql.
>So what he realy does is:
>The first count:
>select count(*)
>from a
>where id not in (select id
> from b)
I'm intrigued by this. I've spent quite a while staring at this and
can't
for the life of me work out why this returns a count of null a.id's.
Surely it must *at least* also include those non-null a.id's that are
not
in b.
I'm suffering badly, please ease my pain :)
>The second count:
>First he must do:
>select a.id, b.id name
>from a, outer b
>where a.id = b.id
>into temp tt_1
>Then the count of null name as he says:
>select count(*) from tt_1 where name is null
>Which should return the same count as the first
Yours in the wilderness of the SQL soul,
Bryan Tonnet
batonnet@zeta.org.au
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