Re: Ask for a query

Pickleman wrote:
> Hello,
>
> I've got two tables, named Order and Customer. I want a query that let
> me see during a period per month wich customer bought something for the
> first time.
>

<snip>

Which customer(s) bought something for the first time EVER? If so, you need to think a little further down the road. Eventually you will need to purge old orders from the database. You may keep them 6 months, a year, 10 years, who knows? That's a business decision, but eventually you will have to implement some purge criteria. If it is important to keep up with when a particular customer placed their first order (or even simply if the current order *is* the first) then you need to consider how you keep that information through the purge.

All too often I find that projects never consider data retention policy as part of the design. "We'll address that in Phase II". And Phase II never comes. Until they run out of disk space. Then a purge is hasitly instituted with no thought of how it impacts basic operations and assumptions. Received on Thu Sep 07 2006 - 07:23:25 CDT