On Mar 12, 2009, at 5:50 PM, James B. Byrne wrote:
>
> ...
> and c.date_effective_from >= <transaction_date>
> and c.date_superseded_after <= <transaction_date>
>
> Have I understood things aright?
The one problem I foresee is that changes to the commodity_tax_rates
table may not reflect in transaction dates that have passed. What
happens if a tax is retroactively ended or applied outside these
barriers? Is this tax calculation frozen at the date of the "best
information we have"? If so, you might consider an insert-only table
and linking the tax decision to the row that happened to be in effect
at any time. This would likely require adding a column indicating when
the row was inserted.
Cheers,
M
