From: T E Schmitz <mailreg@numerixtechnology.de>
To: William Leite Araújo <william.bh@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: join table with itself?
Date: Thu, 15 Mar 2007 18:54:45 +0000
Message-ID: <45F99675.5050801@numerixtechnology.de> (raw)
In-Reply-To: <bc63ad820703150857h2ff195b0wac18476730b19c3c@mail.gmail.com>
References: <45F96A04.7020307@numerixtechnology.de>
<bc63ad820703150857h2ff195b0wac18476730b19c3c@mail.gmail.com>
William Leite Araújo wrote:
> On 15/03/07, *T E Schmitz* <mailreg@numerixtechnology.de
> <mailto:mailreg@numerixtechnology.de>> wrote:
> (...)
>
> Try join the tables.
>
> SELECT present.day, present.low, (MIN(future.day)-present.day) as
>
> days2fall FROM history AS present JOIN history AS future ON (
> present.day < future.day AND
> future.low <= present.low )
> GROUP BY present.day,present.low
> ORDER BY days2fall DESC
That produces the same result as my previous example but maybe the join
is more efficient, Thank you for the suggestion.
However, I am still stuck as to how to retrieve HIGHEST. The result set
produced by the above query only contains those tuples whose LOW is
lower than present.LOW.
For HIGHEST, I need to look at the rows between present.day and DAYS2FALL:
something like
SELECT MAX (high) from history WHERE day >= present.day AND day <
(present.day + days2fall)
-
Regards,
Tarlika Elisabeth Schmitz
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: mailreg@numerixtechnology.de, william.bh@gmail.com
Subject: Re: join table with itself?
In-Reply-To: <45F99675.5050801@numerixtechnology.de>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox