From: | Nabil Sayegh <postgresql(at)e-trolley(dot)de> |
---|---|
To: | pgsql-novice <pgsql-novice(at)postgresql(dot)org> |
Subject: | DISTINCT ... ORDER BY |
Date: | 2003-11-05 00:48:20 |
Message-ID: | 3FA848D4.3070202@e-trolley.de |
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Thread: | |
Lists: | pgsql-novice |
Hi all,
I have built a query that mainly orders all columns.
It shouldn't matter how it orders but FYI:
I need to order by 1 given column and then by all others from 'left to right'.
No problem so far.
Then I want to return only 1 column (e.g. the 3rd) with duplicates removed
_AND_ still in the same order like above.
e.g.:
myCol
-----
a
a
c
b
b
c
b
should return:
myDistinctOrderedCol
--------------------
a
c
b
The problem is that DISTINCT complains about ORDER BY entries not being in the target list.
Any idea ?
Example:
initial query:
SELECT * FROM tab ORDER BY col_2='foo' DESC, col_1='bar' DESC, col_3='blah' DESC;
Then something like:
SELECT DISTINCT col3 FROM {initial query};
TIA
--
e-Trolley Sayegh & John, Nabil Sayegh
Tel.: 0700 etrolley /// 0700 38765539
Fax.: +49 69 8299381-8
PGP : http://www.e-trolley.de
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