Re: order by, but eliminating dupes

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От Jeffrey Melloy
Тема Re: order by, but eliminating dupes
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Msg-id CBB65ED2-DE9E-11D7-B534-000393C78AC0@visualdistortion.org
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Ответ на order by, but eliminating dupes  (LH <_pgsql-novice_@geekhouse.no-ip.com>)
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Something like this works:
select a,b,c from t1 group by a,b,c order by min(q)

Jeff
On Wednesday, September 3, 2003, at 09:52  PM, LH wrote:

> So lets say I got a table A(x,y,z, Q) ordered by column Q, with
> contents
> like so:
>
> x      y      z    Q
> ------------------------
> 21    5      x     1
> 21    5      x     2
> 43   10      t     3
> 1     2       a     5
> 43   10      t     10
> 21    5      x     50
>
> what I would like is to take the results of this query, and maintaining
> the order, only list x, y, z , AND
> not list any duplicates.
>
> So the result I'd want after getting this query would be:
>
> x     y     z
> ----------------
> 21    5    x
> 43   10    t
> 1      2    a
>
> So I'm pulling the results as they come along, and ignore any
> subsequent
> dupes.
>
> I don't know if this is even possible. I've tried combinations of
> SELECT
> DISTINCT, GROUP BY, and others
> with
> no luck. The best I could do was to do the order by in a subquery, then
> do a SELECT UNIQUE on the subquery.
> But that kills the order of the subquery. I've tried group by x,y,z but
> then I can't ORDER BY Q.
>
> - L
>
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster


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