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Date: Sat, 24 Oct 2009 11:58:37 +0200
From: Sylvain Leroux <sl20@wanadoo.fr>
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To: Derby Discussion <derby-user@db.apache.org>
Subject: Re: time format (or: the curse of dst)
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Hi Fabio,

Maybe this is overly simplistic, but why not storing *GMT* datetime?

In that eventuality, some custom written functions would also be necessary to 
convert from/to your specific time format.

Sylvain

Fabio a �crit :
> 
> Hello,
> 
> I'm using Apache Derby to store hourly values of electricity 
> consumption. The values are used in an electricity market simulation 
> implemented in Java.
> 
> Now because of DST, hourly values mean that (for central Europe):
> - one day in March has 23 hours (there's no 2 a.m. to 3 a.m. during that 
> night)
> - one day in October has 25 hours (2 a.m. to 3 a.m. appears twice during 
> that night)
> 
> The data in October is published as:
> (..)
> 02:00
> 3A:00
> 3B:00
> 04:00
> 05:00
> (..)
> 
> I have yet to find a good solution on how to store this data in the 
> database. Obviously, "3A:00" is not a valid time format.
> Currently, I'm storing the consumption data in conjunction with a field 
> named "hour_in_year" (1-8760) but having the date and time is more handy 
> for sql select queries.
> 
> Any ideas how to support the "curse of dst" in a time field?
> 
> Fabio
> 
> 


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