On 4/18/2009 10:37 AM, Darren Norris wrote:
I have a little database (attached) and the dates in one of the tables
(I haven't checked others) change when the file is copied between
different laptops.
The data doesn't change - the representation does - see below.
........
........
Darren
Hi Darren,
Most likely it is Time Zone differences with the user local.
HSQLdb does not have a timezone component (not that most DBMS' do) to
date or time types.
Actually to be more precise I change that to - HSQLdb stores time with
only one timezone - UTC 0
Your local time zone settings (your OS settings) are used to convert
this value when it is used in a recordset. (such as displayed in a form
or on a report)
To see this in action you simply need to enter a date value - exit OO.o
- change your timezone in your OS - restart OO.o, open the file and view
that date/time again.
Here is the comment about this from the HSQLdb source file for timestamps:
57 * HSQLDB uses the client and server's default timezone for all
DATETIME
58 * operations. It stores the DATETIME values in .log and .script
files using
59 * the default locale of the server. The same values are stored as
binary
60 * UTC timestamps in .data files. If the database
is trasported from one
61 * timezone to another, then the DATETIME values in cached tables
will be
62 * handled as UTC but those in other tables will be treated as
local. So
63 * a timestamp representing 12 noon stored in Tokyo timezone will
be treated
64 * as 9 pm in London when stored in a cached table but the same
value stored
65 * in a memory table will be treated as 12 noon.
(*NOTE* - for Base embedded files the tables are 'cached' tables, as
referred to above )
So the top question is, I suppose, "How do you need to handle that, for
your particular application?
What about these:
Is it enough to know that the times each of you are seeing are relative
to your locale?
You don't input date/time data for a different timezone the your OS is
configured for, do you?
Question is - is there any way to ensure for whatever reason (different
OS, timezone, base version , openoffice settings etc) that a date or a
time remains exactly as entered (without inputting as text)? If not
where should I start looking to make sure dates remain the same (there
are 3 different people all with vista laptops and the .odb file will be
emailed, copied via cd / usb between us).
Should be, shouldn't there? (thinking...)
Kind of OT - this is true for the version of HSQLdb shipped with OO.o,
version 1.8.x. The alpha release of HSQLdb 1.9 adds two new data types
to address this particular situation with "TIME WITH TIME ZONE and
TIMESTAMP WITH TIME ZONE". Whether Base will be supporting the newer
HSQLdb engine(s) [2.0 is also in the works] is something I have not seen
mentioned before.
Best wishes,
Drew
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