postgres=# select (101::integer)/(2::integer);
?column?
----------
50
postgres=# select (1.01::numeric)/(2::numeric);
?column?
------------------------
0.50500000000000000000
Rounding errors are something you will need to deal with whether you use INTEGER or NUMERIC fields. You will need to determine what the business logic requirements are for the math. That is, what do your clients expect to happen to fractional units of money? When during manual math operations are dollar values rounded? Make your application work the way your client expects, not the other way around.
I would use NUMERIC since it represents your data most correctly. Using INTEGER for money invariably involves lots of excessive and possibly confusing math with powers of 10. It's very easy to randomly be off by an order of magnitude. With money, that's *bad*. INTEGER math also forces you to always silently truncate fractional cents. That may not be what you want.
--
Brandon Aiken
CS/IT Systems Engineer
________________________________________
From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx] On Behalf Of Yonatan Ben-Nes
Sent: Monday, December 11, 2006 10:51 AM
To: pgsql-general@xxxxxxxxxxxxxx
Subject: [GENERAL] Numeric or Integer for monetary values?
Hi all,
I need to decide which data type should I make for monetary values, shall I use Numeric data type to hold values like "9.52" or is it better to keep it as an integer with value in cents like "952"?
I know that at the manual it's written about the Numeric data type that "It is especially recommended for storing monetary amounts and other quantities where exactness is required.", but I'm wondering what will happen at cases when I got $1.01 to divide between 2 entities at 50% each, if both will get 51 cents or 50 cents it will be a mistake.
The calculation procedure will probably be made with PL/pgSQL, actually maybe it doesn't even matter what the data type is (Integer/Numeric) as long as I make enough validations for the result?
Cheers!
Ben-Nes Yonatan
