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Re: self defined counter function

From: "Paul Breen" <pbreen(at)computerpark(dot)co(dot)uk>
To: "Enrico Ortmann" <pg(dot)admin(at)radax(dot)net>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: self defined counter function
Date: 2004-04-20 11:41:35
Message-ID: 57529. (view raw, whole thread or download thread mbox)
Lists: pgsql-admin
Hello Enrico,

You could try this.

  create table codes (code_urn integer, code char(1));
  create sequence code_urn_seq minvalue 0 maxvalue 35 cycle;

  insert into codes values(0,'0');
  insert into codes values(35,'Z');

Then the following query would give you the incrementing code purely in
the db without having to pull the sequence number back into you app. to
encode it.

  select code from codes where code_urn = (select nextval('code_urn_seq'));

Hope this helps - Paul

> Hi admins,
> I got a conceptual question on creating a stored procedure
> I need for my app. First the description of the problem:
> I need a counter which works with 36 possible values per
> character [0-9 and thereafter A-Z].
> That means if incremented it should return values as follows:
>     0000
>     0001
>     0002
>     ...
>     0009
>     000A
>     000B
>     000C
>     ...
>     000X
>     000Y
>     000Z
>     0010
>     0011
>     0012
>     ...
> and so on.
> My question is if anybody has already implemented such a
> user-defined 'sequence' in PL/PGSql or if anyone has a great
> idea on how to do that. The only solution I see at present is
> to do that in PHP which is used to code the mentioned userland.
> I suggest to solute on doing the following.
>  - I create a sequence on the DBS
>  - I get the next value of this sequence
>  - I convert the next value in PHP in the code I need
> The problem I see on doing this is that I always need to
> convert if I want to get any kind of information about the
> counter. For example it could be that I only want to know
> what the last given value was. Because of the high traffic
> value on the application I have to take care of, that the
> information I read is quite correct at any time. So if I
> have to convert the value of the sequence therefore I need
> a little time. In the meantime the value could have changed
> and my information is worthless.
> I think the best way would be to code a store procedure
> for the problem. Any ideas would be welcome.
> Enrico Ortmann
> ---------------------------(end of broadcast)---------------------------
> TIP 8: explain analyze is your friend

Paul M. Breen, Software Engineer - Computer Park Ltd.

Tel:   (01536) 417155
Email: pbreen(at)computerpark(dot)co(dot)uk

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