[Babase] Using Datetime columns after all

Karl O. Pinc kop at meme.com
Sun Nov 20 15:10:43 EST 2005


In summary: the design is more or less as now, or actually
as before the foxpro Datetime columns were added (they were
always something of a workaround), but I'll be
getting the times from the Datetime columns,
in some cases, for the conversion
as this is more accurate and allows us to keep
the original data at-hand.

I'll have the interations et-al documented soon, although you're
welcome to look at what's up already.  But, I wanted to make sure
I can still get the times from Datetime -- that nothing had
happened to the data in there.

On 11/20/2005 08:14:41 AM, Catherine Markham (amarkham at Princeton.EDU)  
wrote:
> Hi all,
> 
> I remember asking Karl about date/time columns in general when I first
> started working with the weather data.  We already had a date column,
> but we wanted to add the time as well - I was asking whether this
> could be a separate column or had to be together in one date/time
> field.  I'm still not entirely sure from Karl's email what the answer
> is, but my preference would be the data separated in 2 columns (which
> is the way I have it now).

The answer depends on where in the database we're talking about but
IIRC in the interaction related stuff the dates and times are
separated.

> As for the date/time info from Psion, I always had the impression that
> Psion data were analyzed by considering that each consecutive sample
> is 1 minute from the last sample - regardless of the details of the
> date/time stamp associated with each reading.  Of course that's
> definitely something to check with Susan, but the I thought the
> date/time just reflected when the team got the data entered in Psion
> and was not necessarily associated with the exact time of the
> observation.  I think if you look closely at the time intervals
> between samples, you'll see they certainly aren't always 60 seconds
> apart (as I think the protocol says they should be).

I believe you're right, but I also see no reason for throwing away the
seconds.  It's easy enough to make the database pretend they don't
exist, one way or another.  In some ways they definately come in handy
now and, while I could pre-process this out and discard the extra data,
I'm always of the mind to keep the original data in case you ever
want to re-process it.  Regardless this is a discussion we need to
have and it's probably better to have it once we've documentation
to work from.

> 
> But (here comes my disclaimer...) that's just based on my impression
> after glancing through the Psion related tables - I've never really
> looked at it in more detail beyond that.

We'll definatly talk about it.  In the meantime, has Datetime been
munged anywhere lately?


Karl <kop at meme.com>
Free Software:  "You don't pay back, you pay forward."
                  -- Robert A. Heinlein



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