Distinct on is probably your answer.
Something like
select distinct on(col2) col1,col2,col3
from mytable
The traditional disclamer that goes with this is that distinct on is not SQL
standard and is therefore not portable. But it works very well
HTH
Chad
----- Original Message -----
From: "Jules Alberts" <jules.alberts@arbodienst-limburg.nl>
To: <pgsql-sql@postgresql.org>
Sent: Wednesday, March 12, 2003 3:03 AM
Subject: [SQL] filtering out doubles
> Hello everyone,
>
> I was wondering how to filter out double values (where "value" spans
> two columns COL1 and COL2) with a SELECT statement. If I have this
> table:
>
> COL1 |COL2 |COL3
> -----------------------------
> a |b |some value
> a |b |another value
> a |c |yet another value
>
> what would be the select statement to get this result:
>
> COL1 |COL2 |COL3
> -----------------------------
> a |b |some value
> a |c |yet another value
>
> I was thinking that DISTINCT would do this, but I don't want to loose
> COL3. TIA for any tips!
>
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