There was a discussion about this months ago and I think that the
conclusion was every property should have a valid_from and a valid_to
field [default = end of the universe].
So you can get snapshots for past versions without any magic.
An example for a hypothetic cashflow-database (dates are YYMMDD ) might be:
select * from cf where origin = "wmde" and v2 = 999999 and payment_date
= 130404; -- would give the actual view of future
cashflows coming
from wmde
select * from cf where origin = "wmde" and v2 = 121231 and payment_date
= 130404; -- would give the view of cashflows coming
from wmde seen by
end of year 2012
I don't know if something like this would be easy to add to your
existing database scheme.
Lukas
Am Do 04.04.2013 09:47, schrieb Daniel Kinzler:
On 03.04.2013 23:23, BinĂ¡ris wrote:
A good question from huwiki:
When I click on an earlier version of the page in the history, will the
"then-value" of the property be shown or the current value?
If I read the 2013 version of [[United States of America]] in 2018, will Obama
be the president?
You will see the current value, not the old one. This is the
same as for
templates and images. A "time warp" system that allows us to view old versions
of pages exactly as they were has long been discussed, but is tricky, especially
when templates (or, in the case of wikidata, properties) get deleted or renamed.
Nobody has come up with a good solution yet.
The qualifiers Sven mentioned will allow us to record who was president when in
Wikidata, but when including the "current president" on a Wikipiedia page,
this
will always be the present one, even when looking at old version of the page.
-- daniel