Re: Novice PL/pgSQL question and example

On 2010-02-08, James Long <pgsql-novice(at)museum(dot)rain(dot)com> wrote:

Newsgroups: gmane.comp.db.postgresql.novice
From: Jasen Betts <jasen(at)xnet(dot)co(dot)nz>
Subject: Re: Novice PL/pgSQL question and example
References: <20100208013329(dot)GA95096(at)ns(dot)umpquanet(dot)com>
Organization: Dis (not Dat) Organisation
Followup-To:
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On 2010-02-08, James Long <pgsql-novice(at)museum(dot)rain(dot)com> wrote:
> At least, I hope this is a Novice question. It sure makes me
> feel like one! :) Please cc: me directly on replies, as I might
> miss a reply that goes only to the list.
>
> I'm running PostGreSQL 8.3.9 on FreeBSD 6.4-STABLE, but I doubt
> this is platform-dependent.
>
> I'm trying to solve what I'm sure is a common problem in the
> accounting world. A total cost C has to be split across N
> different accounts, and C is not necessarily divisible by N.
> Shares with fractions of pennies are not allowable, and to make
> the accounting balance, the sum of all the shares has to sum to
> exactly match the total cost C.
>
> It's like splitting a $90 lunch check between 7 people.
>

> This PHP code shows the math I'm using, and works great.

here's different way to do it.

share ( pieces , people, index ) = floor (pieces * (index + 1) / people ) - floor ( pieces * index / people)

you don't need to remember an error just increase the index each time.