From: | Julian Scarfe <jscarfe(at)callnetuk(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-hackers(at)postgreSQL(dot)org, pgsql-sql(at)postgreSQL(dot)org |
Subject: | Re: [SQL] DISTINCT ON: speak now or forever hold your peace |
Date: | 2000-01-25 08:30:36 |
Message-ID: | 388D5F2C.DBD639D@callnetuk.com |
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Lists: | pgsql-hackers pgsql-sql |
Tom Lane wrote:
>
> If I don't hear loud hollers very soon, I'm going to eliminate the
> DISTINCT ON "feature" for 7.0. As previously discussed, this feature
> is not standard SQL and has no clear semantic interpretation.
I use 'distinct on' to get the most recent reports for each of a group of
locations. E.g.:
create table reports (
location varchar(16),
report_time datetime,
report_text text);
select distinct on location * from reports where location ~~ 'Lond%' order by
location, reporttime desc;
to get the tuples that offer the most recent reports for each of London,
Londonderry, Londy etc.
Is there an alternative?
Julian Scarfe
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