From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | oheinz(at)stud(dot)fbi(dot)fh-darmstadt(dot)de |
Cc: | "pgsql-sql(at)postgresql(dot)org" <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Problem using Subselect results |
Date: | 2003-07-29 15:00:56 |
Message-ID: | 22142.1059490856@sss.pgh.pa.us |
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Lists: | pgsql-sql |
oheinz(at)stud(dot)fbi(dot)fh-darmstadt(dot)de writes:
> But as this data is time sensitive, we introduce some kind of time stamp - a
> serial which is global to all tables. Now, for each record in table 'one' i
> want to see only the corresponding records in tables two, three, etc... that
> were created before 'one.updatenr'
> SELECT * FROM one, two WHERE (one.two_id=two.two_id AND one.updatenr >
> two.updatenr);
> This might match multiple records in tables two (two_id is not a pk, we have
> historic records in this table). Now I want only the most current version
> before one.updatenr. - And that's where I run into trouble.
You might be able to make this work by using SELECT DISTINCT ON. See
the "weather reports" example in the SELECT reference page.
regards, tom lane
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