Re: virtual (COMPUTED BY) columns?

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
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Andreas Kretschmer
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