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Query Help using Except
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* Query Help using Except
@ 2003-10-23 18:17  yusuf0478@netscape.net
  0 siblings, 1 reply; 2+ messages in thread

From: yusuf0478@netscape.net @ 2003-10-23 18:17 UTC (permalink / raw)
  To: pgsql-sql

I'm interested in finding the minimim A.id such that the following holds:

select A.charge
    , B.user_id
    , C.employee_id
from A
inner join B using (user_id)
inner join C using (employee_id)

except

select X.charge
    , Y.user_id
    , Z.employee_id
from X
inner join Y using (user_id)
inner join Z using (employee_id)

--

I can't do the following, since the number of selected columns have to match: 

select A.id 
    , A.charge
    , B.user_id
    , C.employee_id
from A
inner join B using (user_id)
inner join C using (employee_id)

except

select X.charge
    , Y.user_id
    , Z.employee_id
from X
inner join Y using (user_id)
inner join Z using (employee_id)


Can someone help me with the query?

Thanks in advance.

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^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: Query Help using Except
@ 2003-10-27 03:34  Bruno Wolff III <bruno@wolff.to>
  parent: yusuf0478@netscape.net
  0 siblings, 0 replies; 2+ messages in thread

From: Bruno Wolff III @ 2003-10-27 03:34 UTC (permalink / raw)
  To: yusuf0478@netscape.net; +Cc: pgsql-sql

On Thu, Oct 23, 2003 at 14:17:08 -0400,
  yusuf0478@netscape.net wrote:
> 
> I can't do the following, since the number of selected columns have to match: 

One option is to use where NOT EXISTS instead of EXCEPT. Another way would
be to add A.id to the rows in the set difference using a join. I expect the
second method would be slower and that you should try using NOT EXISTS.

> 
> select A.id 
>     , A.charge
>     , B.user_id
>     , C.employee_id
> from A
> inner join B using (user_id)
> inner join C using (employee_id)
> 
> except
> 
> select X.charge
>     , Y.user_id
>     , Z.employee_id
> from X
> inner join Y using (user_id)
> inner join Z using (employee_id)



^ permalink  raw  reply  [nested|flat] 2+ messages in thread

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