Re: Chart of Accounts

Hi James,

There is some my publications about SART AML System based on banking
General Ledger (OLAP Data Warehouse and Chart of Accounts as dimension
with 60 000+ items) - may be helpful.

http://www.analyticsql.org/documentation.html
http://www.analyticsql.org/files/AITM-MoneyLaundering.pdf

Regards,
Blazej Oleszkiewicz

2008/10/12 James Hitz <jam_hit@yahoo.com>:
> Dear All,
>
> I have just started experimenting with PGSQL, with a view to migrate from the SQL server I use currently.  I am
tryingto implement an "intelligent" Chart of Accounts for an accounting program.  The following is long-winded but
pleasebear with me: 
>
> I have a table coa (chart of accounts) with the following schema
>
>  CREATE TABLE coa(
>    coa_id serial not null,
>    parent_id int not null default 0,
>    account_name text not null,
>    amt money default 0,
>    primary key(coa_id)
>  );
>
> After populating the database with basic accounts it resembles this (the hierarchy is mine):
>
>  coa_id, parent_id, account_name,          amt
>  0,        -1,      'Chart of Accounts',    0.00
>  1,         0,         'Assets',            0.00
>  5,         1,           'Fixed Assets',    0.00
>  6,         5,             'Motor Van',     0.00
>  --truncated ---
>  2,         0,       'Liabilities',         0.00
>  3,         0,       'Income',              0.00
>  4,         0,       'Expenses',            0.00
>
> So far, so good.  I would like it so that if the amt of a a child account changes, the parent account is updated, if
achild account is deleted, the amount is reduced off of the parent account etc. 
>
> I have managed to achieve this using the following trigger functions:
>
> CREATE OR REPLACE FUNCTION public.coa_del_amt() RETURNS trigger AS
> $body$
> begin
>        update coa set amt = amt - old.amt where coa_id = old.parent_id;
>        return old;
> end;
> $body$
> LANGUAGE 'plpgsql'
>
> ------------------
>
> CREATE OR REPLACE FUNCTION public.coa_ins_amt() RETURNS trigger AS
> $body$
> begin
>        UPDATE coa SET amt = amt + new.amt WHERE coa_id = new.parent_id;
>        return new;
> end;
> $body$
> LANGUAGE 'plpgsql'
>
> ------------
>
> CREATE OR REPLACE FUNCTION public.coa_upd_amt() RETURNS trigger AS
> $body$
> begin
>        IF new.parent_id = old.parent_id THEN
>                UPDATE coa SET amt = amt + (new.amt - old.amt)
>                WHERE coa_id = new.parent_id;
>        ELSE
>                UPDATE coa SET amt = amt - old.amt
>                   WHERE parent_id = old.parent_id;
>                UPDATE coa SET amt = amt + new.amt
>                   WHERE parent_id = new.parent_id;
>        END IF;
>        RETURN new;
> end;
> $body$
> LANGUAGE 'plpgsql'
>
> ------------
>
> These have been bound to the respective ROW before triggers.  And they work as expected upto a certain extent. eg
assigninga value to 'Motor Van' updates the relevant parent accounts: 
>
>  UPDATE coa SET amt = 4000 WHERE coa_id = 6;
>
> The problem comes about when one wants to change the parent account for a sub account eg, assuming in the example
abovethat 'Motor Van' was a liability, attempting to change its parent_id from 1 to 2 is erronous and somewhat
interestingbecause the amt for all related accounts are reset to unpredictible values, AND the parent_id does not
changeanyway. 
>
> The problem lies squarely in the function coa_upd_amt().
>
> Any ideas.
>
> Thank you.
>
>
>
>
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