From: | "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: virtual (COMPUTED BY) columns? |
Date: | 2007-01-28 16:43:42 |
Message-ID: | 20070128164342.GA4647@a-kretschmer.de |
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Lists: | pgsql-general |
am Sun, dem 28.01.2007, um 10:25:33 -0600 mailte Ron Johnson folgendes:
> Hi.
>
> These fields do not use any disk space, as the data in them is
> derived on the fly.
>
> For example:
> CREATE TABLE T_EXAMPLE (
> SOME_DATE DATE,
> JDATE COMPUTED BY EXTRACT(JULIAN FROM SOME_DATE)
> );
>
> A work-around is to create a function, and reference it in every
> query, but storing them in the table definition is the "tidy",
> low-maintenance way to do it.
Was this a question how to do this in PostgreSQL?
You can use a VIEW. Just create T_EXAMPLE ( SOME_DATE DATE );
and then
CREATE VIEW view_example AS SELECT some_date, EXTRACT(JULIAN FROM
some_date) AS julian_date FROM T_EXAMPLE;
Andreas
--
Andreas Kretschmer
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