Re: except command - Mailing list pgsql-admin

From olivier.boissard@cerene.fr
Subject Re: except command
Date
Msg-id 46C0D794.3020105@cerene.fr
Whole thread Raw
In response to Re: except command  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
List pgsql-admin
Yes
 I noticed  It was not an ANSI sql operator
I think it's a good solution to spare temporay tables or result set

I was searching a way to ease some réplication scripts but I don't think
it will help me.
It's better to use it to get a couple of records inside complex queries
from many tables .

Thanks for help

Olivier

Kevin Grittner a écrit :
>>>> On Mon, Aug 13, 2007 at  4:30 PM, in message <46C0CD72.5090407@cerene.fr>,
>>>>
> "olivier.boissard@cerene.fr" <olivier.boissard@cerene.fr> wrote:
>
>> So it's like a filter on the first query
>>
>
> Exactly; I think that sums it up better than anything I said.
>
> By the way, it does strike me as an odd omission that there is no set
> operator in the ANSI standard to get you directly to the set of disjoint
> elements.  With two datasets, a and b, you could always get there with:
>
> (a EXCEPT b) UNION ALL (b EXCEPT a)
>
> or with:
>
> (a UNION ALL b) EXCEPT (a INTERSECT b)
>
> Of course, you could store the sets in temporary tables to get there without
> generating from scratch each time, if that is expensive.
>
> -Kevin
>
>
>
>
>


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