SQL Server version 2016 résoudra ce problème une fois pour toutes . Pour les versions antérieures, une solution CLR est probablement la plus simple. Ou pour une règle DST spécifique (comme aux États-Unis uniquement), une fonction T-SQL peut être relativement simple.
Cependant, je pense qu'une solution générique T-SQL pourrait être possible. Tant que xp_regread
ça marche, essayez ceci:
CREATE TABLE #tztable (Value varchar(50), Data binary(56));
DECLARE @tzname varchar(150) = 'SYSTEM\CurrentControlSet\Control\TimeZoneInformation'
EXEC master.dbo.xp_regread 'HKEY_LOCAL_MACHINE', @tzname, 'TimeZoneKeyName', @tzname OUT;
SELECT @tzname = 'SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\' + @tzname
INSERT INTO #tztable
EXEC master.dbo.xp_regread 'HKEY_LOCAL_MACHINE', @tzname, 'TZI';
SELECT -- See http://msdn.microsoft.com/ms725481
CAST(CAST(REVERSE(SUBSTRING(Data, 1, 4)) AS binary(4)) AS int) AS BiasMinutes, -- UTC = local + bias: > 0 in US, < 0 in Europe!
CAST(CAST(REVERSE(SUBSTRING(Data, 5, 4)) AS binary(4)) AS int) AS ExtraBias_Std, -- 0 for most timezones
CAST(CAST(REVERSE(SUBSTRING(Data, 9, 4)) AS binary(4)) AS int) AS ExtraBias_DST, -- -60 for most timezones: DST makes UTC 1 hour earlier
-- When DST ends:
CAST(CAST(REVERSE(SUBSTRING(Data, 13, 2)) AS binary(2)) AS smallint) AS StdYear, -- 0 = yearly (else once)
CAST(CAST(REVERSE(SUBSTRING(Data, 15, 2)) AS binary(2)) AS smallint) AS StdMonth, -- 0 = no DST
CAST(CAST(REVERSE(SUBSTRING(Data, 17, 2)) AS binary(2)) AS smallint) AS StdDayOfWeek, -- 0 = Sunday to 6 = Saturday
CAST(CAST(REVERSE(SUBSTRING(Data, 19, 2)) AS binary(2)) AS smallint) AS StdWeek, -- 1 to 4, or 5 = last <DayOfWeek> of <Month>
CAST(CAST(REVERSE(SUBSTRING(Data, 21, 2)) AS binary(2)) AS smallint) AS StdHour, -- Local time
CAST(CAST(REVERSE(SUBSTRING(Data, 23, 2)) AS binary(2)) AS smallint) AS StdMinute,
CAST(CAST(REVERSE(SUBSTRING(Data, 25, 2)) AS binary(2)) AS smallint) AS StdSecond,
CAST(CAST(REVERSE(SUBSTRING(Data, 27, 2)) AS binary(2)) AS smallint) AS StdMillisec,
-- When DST starts:
CAST(CAST(REVERSE(SUBSTRING(Data, 29, 2)) AS binary(2)) AS smallint) AS DSTYear, -- See above
CAST(CAST(REVERSE(SUBSTRING(Data, 31, 2)) AS binary(2)) AS smallint) AS DSTMonth,
CAST(CAST(REVERSE(SUBSTRING(Data, 33, 2)) AS binary(2)) AS smallint) AS DSTDayOfWeek,
CAST(CAST(REVERSE(SUBSTRING(Data, 35, 2)) AS binary(2)) AS smallint) AS DSTWeek,
CAST(CAST(REVERSE(SUBSTRING(Data, 37, 2)) AS binary(2)) AS smallint) AS DSTHour,
CAST(CAST(REVERSE(SUBSTRING(Data, 39, 2)) AS binary(2)) AS smallint) AS DSTMinute,
CAST(CAST(REVERSE(SUBSTRING(Data, 41, 2)) AS binary(2)) AS smallint) AS DSTSecond,
CAST(CAST(REVERSE(SUBSTRING(Data, 43, 2)) AS binary(2)) AS smallint) AS DSTMillisec
FROM #tztable;
DROP TABLE #tztable
Une fonction T-SQL (complexe) pourrait utiliser ces données pour déterminer le décalage exact pour toutes les dates pendant la règle DST actuelle.