From: Jan Wieck <janwieck@Yahoo.com>
Message-Id: <200008302214.RAA06005@jupiter.jw.home>
Subject: Re: function
In-Reply-To: <078001c0129a$a2354ec0$1708050a@mt.lv> from Normunds at "Aug 30,
	2000 05:54:51 pm"
To: Normunds <normunds@mt.lv>
Date: Wed, 30 Aug 2000 17:14:10 -0500 (EST)
CC: pgsql-general@postgresql.org, pgsql-sql@postgresql.org
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Normunds wrote:
> Hi all,
>
> how can I write function which takes text from one field, replaces
> some characters and puts it in other field? I have array with old and
> new values.
>
> For example:
> old array = {'r', 'Z', 'o'}
> new array = {'s', 'm', 't'}
> old field value = 'Zorro'
> new field value which must calculate this function = 'mtsst'
>
> This function will be used in update trigger.
> Any ideas?

    Tcl  has  a  "map" functionality as subcommand of "string". I
    think it appeared in version 8.1.  To use the example  below,
    your  Tcl  installation  must be 8.1 or newer when rebuilding
    PostgreSQL configured with  "--with-tcl"  and  enable  PL/Tcl
    with "createlang".

      CREATE FUNCTION string_map(text, text) RETURNS text AS '
          return [string map $2 $1]
      ' LANGUAGE 'pltcl';
      CREATE
      SELECT string_map('Zorro', 'r s Z m o t');
       string_map
      ------------
       mtsst
      (1 row)

    As  you  see,  the old and new arrays are both coded into the
    second argument. It is a key, value pair list, with usual Tcl
    quoting for lists. Can you convert your arrays to that?


Jan

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