[AccessD] RE: Getting Started

On 4 Jun 2004 at 12:50, Jim Lawrence (AccessD) wrote:

> Just thought I would add my comments to this discussion.
> 
> There is always going to be round-off issue with numeric data. To keep these
> problems to minimum it is advisable to process the round-off at the time of
> entry.
> 
> Given: A tax that is 7.5% of an invoice total.
> When calculated, on say $115.18 the amount is total invoice is $123.8185
> with tax being  $8.6385. The amount that will be paid is $123.82 with the
> tax being $8.64. These are the two numbers that stored not the raw
> uncalculated tax and invoice values.
> 
> At the end of the fiscal year the tax totals can just be added and the
> summary will perfectly match the invoice total. A value, in a database that
> has to be added and then round-off performed will result in differences and
> accumulative errors.
> 

And use currency datatypes, because even with rounding of all individual 
values, you can still run into trouble with least significant bits in 
singles/doubles because of the way they are stored.



 
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