Re: [HACKERS] math error or rounding problem Money type

Justin wrote:
> yes. The question is why are the to sides not equal anymore
>
> Take this
>
> Select
> '2',
> round(sum( beginBalance ),6) as beginbalance,
> round(sum( negative ),6) as debit,
> round(sum( positive ),6) as credit,
> round(sum( difference ),6) as difference,
> round(sum( endbalance),6) as endbalance
> from trailbalance
> union
> Select
> '1',
> sum( round(beginBalance,6)) as beginbalance,
> sum( round(negative,6)) as debit,
> sum( round(positive,6)) as credit,
> sum( round(difference,6)) as difference,
> sum( round(endbalance,6)) as endbalance
> from trailbalance
>
> "1" -0.000006 -11250546.743752 11250546.743752 0.000000
> -0.000007
> "2" 0.000000 -11250546.743752 11250546.743752 0.000000
> 0.000000
>
> At the very least this show a clear warning when rounding do it after
> all the sum function is called not before.
>

IFAIK (dimly recalling numerical analysis courses at university) SUM and
ROUND can *never* be commuted. In general the recommended approach is to
round as late as possible and as few times are possible - so your 1st
query is the correct or best way to go.

Cheers

Mark

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