From: | Mike Rylander <mrylander(at)gmail(dot)com> |
---|---|
To: | Rick Schumeyer <rschumeyer(at)ieee(dot)org>, PgSql General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: sorting library of congress numbers |
Date: | 2005-01-19 23:09:50 |
Message-ID: | b918cf3d0501191509631db880@mail.gmail.com |
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Lists: | pgsql-general |
On Wed, 19 Jan 2005 17:37:20 -0500, Rick Schumeyer <rschumeyer(at)ieee(dot)org> wrote:
>
> I have a table where one of the columns is a library of congress number.
>
> I would like to be able to ORDER BY this column.
>
First off, by LOC numbers do you mean Title Control Numbers like
"o00325992" or "i0824506030" with an optional vendor name in front of
them?
>
>
> Currently, the column is a varchar. Unfortunately, a normal string
> comparison will not work.
>
>
> First, has anyone done this already?
>
If you mean ISBN or ISSN numbers then there is a contrib module that
may help, though I don't think it implements a new type, just
functions to validate and generate them.
>
> If not, I'm thinking I would need to:
>
> 1) define a new type to hold LOC numbers.
>
> 2) write a function that determines less than, greater than
>
>
>
> It seems like I'm missing something here. I have not yet defined a new type…is defining less/greater part of that process?
> Is there a simpler way to do this?
You could probably just write some comparison functions, create a new
operator class, and assign them names like "~>" and "~<". See the
documentation here:
http://www.postgresql.org/docs/8.0/interactive/xoper.html .
--
Mike Rylander
mrylander(at)gmail(dot)com
GPLS -- PINES Development
Database Developer
http://open-ils.org
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