Updating a SQL table with values from different rows in itself - sql-server-2005

Question

I have a table
with 5 columns :-
Country Code
Language
Warehouse
ActiveFrom
ActiveTo
A subset of data (apologies for the column headers being out of alignment:-
Country
Code
Language
Warehouse
ActiveFrom ActiveTo
AT de BHU 2011-08-08 00:00:00.000 9999-12-31 23:59:59.000
AT de WGN 2011-02-14 00:00:00.000 9999-12-31 23:59:59.000
BE fr BHU 2011-09-01 00:00:00.000 9999-12-31 23:59:59.000
BE fr WGN 2011-02-14 00:00:00.000 9999-12-31 23:59:59.000
CH de WGN 2011-02-14 00:00:00.000 9999-12-31 23:59:59.000
CZ sk BHU 2011-08-08 00:00:00.000 9999-12-31 23:59:59.000
CZ sk WGN 2011-02-14 00:00:00.000 9999-12-31 23:59:59.000
DE de BHU 2011-09-01 00:00:00.000 9999-12-31 23:59:59.000
DE de WGN 2011-02-14 00:00:00.000 9999-12-31 23:59:59.000
What I want to do, is update the ActiveTo column, to the value of the ActiveFrom Date (give or take a few milliseconds) for the same warehouse.
I've tried This :-
update Translations
set ActiveTo = DateAdd(ms, -3, ot.ActiveFrom)
from Translations ot
Where Warehouse = 'WGN'
and CountryCode = ot.CountryCode
but, it gives these results.
CountryCode Language Warehouse ActiveFrom ActiveTo
AT de BHU 2011-08-08 00:00:00.000 9999-12-31 23:59:59.000
AT de WGN 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997
BE fr BHU 2011-09-01 00:00:00.000 9999-12-31 23:59:59.000
BE fr WGN 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997
CH de WGN 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997
CZ sk BHU 2011-08-08 00:00:00.000 9999-12-31 23:59:59.000
CZ sk WGN 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997
DE de BHU 2011-09-01 00:00:00.000 9999-12-31 23:59:59.000
DE de WGN 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997
It's updating the right rows. But the value is wrong, it's deducting 3 milliseconds from its own ActiveFrom Date, instead of the other warehouse start date.
This SQL gives the right results in a derived table:-
select t.CountryCode, t.Warehouse, DateAdd (ms, -3, ot.ActiveFrom) as 'TransferToBHU', t.ActiveFrom, t.ActiveTo,
ot.CountryCode, ot.Warehouse, ot.ActiveFrom, ot.ActiveTo
from Translations t
inner join Translations ot
on ot.CountryCode= t.CountryCode
Where t.Warehouse = 'WGN'
and ot.Warehouse = 'BHU'
Order by t.CountryCode
CountryCode Warehouse TransferToBHU ActiveFrom ActiveTo CountryCode Warehouse ActiveFrom ActiveTo
AT WGN 2011-08-07 23:59:59.997 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997 AT BHU 2011-08-08 00:00:00.000 9999-12-31 23:59:59.000
BE WGN 2011-08-31 23:59:59.997 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997 BE BHU 2011-09-01 00:00:00.000 9999-12-31 23:59:59.000
CZ WGN 2011-08-07 23:59:59.997 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997 CZ BHU 2011-08-08 00:00:00.000 9999-12-31 23:59:59.000
DE WGN 2011-08-31 23:59:59.997 2011-02-14 00:00:00.000 2011-02-13 23:59:59.997 DE BHU 2011-09-01 00:00:00.000 9999-12-31 23:59:59.000
Now, if I could get the calculated value in 'TransferToBHU' into the update value, that's exactly what I want.
The simplest solution would update the 'WGN' warehouse values based on the 'BHU' values. However, the best would update based on getting the two latest ActiveFrom dates for a given CountryCode.
Either solution is acceptable, although if anyone supplies one that works on the dates - they will get the accepted answer.
Thanks in advance.

Answer 1

update t1
set ActiveTo = DateAdd(ms, -3, t2.ActiveFrom)
from Translations t1
JOIN
Translations t2 ON t1.CountryCode = t2.CountryCode
Where t1.Warehouse = 'WGN' AND t2.Warehouse = 'BHU'
Of course, country CH has no BHU row, so:
update t1
set ActiveTo = DateAdd(ms, -3, ISNULL(t2.ActiveFrom,t1.ActiveFrom))
from Translations t1
LEFT JOIN
Translations t2 ON t1.CountryCode = t2.CountryCode
Where t1.Warehouse = 'WGN' AND t2.Warehouse = 'BHU'