From: Neil Tompkins
Date: September 5 2010 6:32am
Subject: Re: Best method to keep totals
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Thanks for all the useful information. I'm going to ensure the  
relevant fields are indexed and our db is optimised.



On 4 Sep 2010, at 16:10, Arthur Fuller <fuller.artful@stripped> wrote:

> 100% agreed.
>
> Arthur
>
> The other exception is also where financial data is being stored. If  
> you
>> have, say, a database containing sales order records, then as well as
>> storing the individual values of each item in each order, you also  
>> need to
>> store the total value of the order, the total price charged to the  
>> customer
>> and the total paid by the customer. These three should, of course,  
>> be not
>> only identical to each other but also to the sum of the individual  
>> items, so
>> there is not only duplication but the potential for skew. But that,  
>> of
>> course, is precisely *why* you store them, as any discrepancy  
>> indicates an
>> error which needs to be investigated.
>>
>> Mark
>>