Message-ID: <20030820212854.13264.qmail@web41605.mail.yahoo.com>
Date: Wed, 20 Aug 2003 14:28:54 -0700 (PDT)
From: George McQuade <josslad@yahoo.com>
Subject: Re: Table conversion query...
To: Joe Conway <mail@joeconway.com>
Cc: pgsql-sql@postgresql.org
In-Reply-To: <3F43D7E9.2000804@joeconway.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii


--- Joe Conway <mail@joeconway.com> wrote:
> George McQuade wrote:
> > date     tran gl    amt
> > 08/20/03 1001 3010   -30.00
> > 08/20/03 1001 1030  -300.00
> > 08/20/03 1001 1060  +330.00
> > 08/20/03 1002 ...next transaction
> > ...
> >  and I need to convert to:
> > 
> > date     glcr gldb  amt
> > 08/20/03 1060 3010  30.00
> > 08/20/03 1060 1030 300.00
> > 
> > in other words, the negative gl's go into gldb
> > and they make up the total for the positive gl.
> > 
> > is there a way to accomplish this in postgresql?
> > or should I implement it inside the java app?
> 
> There's no simple way to do this in Postgres. You
> could do it with a 
> PL/pgSQL table function, or for better performance a
> C function. 

Interesting, my C is gone a long time ago. Would the 
table function be fairly complex for someone who's
never done one?
I'm tempted by the java option, but initial jdbc speed
tests don't look very promising (the avg file has
1/2 million records).

> There are a couple of questions yet to be answered 
> though:
> 1) Can there ever be more than one credit account,
> e.g. -30, -300, +150, +180?

No, so far all the examples I've seen involve a single
credit account.

> 2) What happens if sum(neg values) != sum(pos
> values)? Throw an error?

Yes, this would indicate a system out of balance
that requires external assistance.

Thanks for the help.

george


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