我正在面对一个SQL Server数据库，其中包含存储在本地时间中的许多DateTime个值。 （是的，这很不幸！）我们可能有5到10年的数据，这意味着如果相关区域遵守夏令时，此位置的UTC偏移将更改，具体取决于一年中的时间时间，当然还有发生变化的时间表也可能会发生变化，例如2007年在美国（这些数据大部分来自）的情况就是如此。
我的目标是在SQL级别将这些DateTime转换为UTC时间。如果没有加载整个Olson or TZ Database并查询它，是否有人有将历史本地时间戳转换为UTC时间的技术？ [如果它有帮助，方便的话，我们恰好也有每行的纬度和经度（可用于识别时区。）
注意：对于实时编写的行，DATEDIFF(Hour, Getutcdate(), GETDATE()) AS UtcOffset的技巧当然可以正常工作。问题是将此追溯应用于夏令时“屏障”两侧发生的日期。
答案 0 :(得分：1)
您可以使用AT TIME ZONE转换为UTC。 SQL知道切换到夏令时，因此可以解决。您只需找出时区（如您所说，使用纬度和经度即可。）
您可以从此处获取所有时区： 选择*从sys.time_zone_info
因此解决方案将是这样的： 首先，在您的表格中添加带有时区的列（您可以使用纬度和经度找到该列）。 然后使用“ AT TIME ZONE”更新您的（新添加的）UTC日期列，例如：
-- some sample data to play with
CREATE TABLE #YourTable
(
LocalDateTime DATETIME,
[UtcDateTime] DATETIMEOFFSET,
TimeZoneName VARCHAR(100)
);
INSERT INTO #YourTable
(
LocalDateTime,
TimeZoneName
)
VALUES
('20150101', 'Alaskan Standard Time'),
('20150101', 'US Mountain Standard Time'),
('20190701', 'Alaskan Standard Time'),
('20190701', 'US Mountain Standard Time');
-- convert to UTC
UPDATE #YourTable
SET [UtcDateTime] = LocalDateTime AT TIME ZONE TimeZoneName AT TIME ZONE 'UTC';
-- check results
SELECT * FROM #YourTable;
答案 1 :(得分：0)
这是基于Chris Barlow之前的回答，
SQL Server - Convert date field to UTC
这是一个SQL Server 2008视图形式的解决方案组件，其中包含用于历史数据转换的夏令时（DST）规则方法。
（不需要纬度/长数据。）
您可以使用此视图创建引用更新的自定义解决方案，即可能需要转换的本地表列，例如dbo.mytable.created_date。
下面引用了有关使用视图的一些注意事项，感兴趣的是＆＃34;示例用途 - 用于历史数据转换＆＃34;：
--
-- DATETIME VS. DATETIMEOFFSET
--
-- WHERE, t = '2016-12-13 04:32:00'
--
declare
@Sydney DATETIME
set
@Sydney = '2016-12-13 04:32:00'
select
Sydney = @Sydney
declare
@Sydney_UTC DATETIMEOFFSET
set
@Sydney_UTC = '2016-12-13 04:32:00.6427663 +10:00'
select
Sydney_UTC = @Sydney_UTC
declare
@NewYork DATETIME
set
@NewYork = '2016-12-13 04:32:00:34'
select
NewYork = @NewYork
declare
@NewYork_UTC DATETIMEOFFSET
set
@NewYork_UTC = '2016-12-13 04:32:00.6427663 -04:00'
select
NewYork_UTC = @NewYork_UTC
select
DATEDIFF(hh, @Sydney, @NewYork) as DIFF_DATETIME
select
DATEDIFF(hh, @Sydney_UTC, @NewYork_UTC) as DIFF_DATETIMEOFFSET
--
-- LOCAL UTC OFFSET FOR REAL-TIME DATA TODAY
--
select
DATEDIFF( Hour, GETUTCDATE(), GETDATE() ) AS UtcOffset
--
-- LOCAL UTC DATE FOR REAL-TIME DATA TODAY - EASTERN STANDARD EXAMPLE
--
select
convert( datetimeoffset( 5 ), GETDATE(), 120 )
--
-- EXAMPLE USAGE -
--
select
*
from
vw_datetime__dst__timezone
--
-- EXAMPLE USAGE - FOR HISTORICAL DATA CONVERSION - EASTERN STANDARD
--
select
created_date,
isnull( dst.zone, 'NO TZ' ) as zone,
isnull(
case
when created_date >= dstlow and
created_date < dsthigh
then dst.daylight
else dst.standard
end,
'NO OFFSET'
) as zone_offsettime,
TODATETIMEOFFSET(
created_date,
case
when created_date >= dstlow and
created_date < dsthigh
then dst.daylight
else dst.standard
end
) as zone_time,
SWITCHOFFSET(
TODATETIMEOFFSET(
created_date,
case
when created_date >= dstlow and
created_date < dsthigh
then dst.daylight
else dst.standard
end
),
'+00:00' -- parameterize?
) as utc_time
from
(
select GETDATE() as created_date
union
select SYSDATETIMEOFFSET() as created_date
union
select '2017-01-01 15:20:24.653' as created_date
) DYNAMIC_temp_table
left outer join vw_datetime__dst__timezone dst on
created_date between yrstart and yrend and
dst.zone = 'ET'
order by
created_date
- 这是视图SQL：
drop view
vw_datetime__dst__timezone
go
create view
vw_datetime__dst__timezone
as
select
yr,
zone,
standard,
daylight,
rulename,
strule,
edrule,
yrstart,
yrend,
dateadd(day, (stdowref + stweekadd), stmonthref) dstlow,
dateadd(day, (eddowref + edweekadd), edmonthref) dsthigh
from (
select
yrs.yr,
timezone.zone,
timezone.standard,
timezone.daylight,
timezone.rulename,
dst_rule.strule,
dst_rule.edrule,
yrs.yr + '-01-01 00:00:00' yrstart,
yrs.yr + '-12-31 23:59:59' yrend,
yrs.yr + dst_rule.stdtpart + ' ' + dst_rule.cngtime stmonthref,
yrs.yr + dst_rule.eddtpart + ' ' + dst_rule.cngtime edmonthref,
case
when dst_rule.strule in ('1', '2', '3')
then
case
when datepart(dw, yrs.yr + dst_rule.stdtpart) = '1'
then 0
else 8 - datepart(dw, yrs.yr + dst_rule.stdtpart)
end
else (datepart(dw, yrs.yr + dst_rule.stdtpart) - 1) * -1
end as stdowref,
case
when dst_rule.edrule in ('1', '2', '3')
then
case
when datepart(dw, yrs.yr + dst_rule.eddtpart) = '1'
then 0
else 8 - datepart(dw, yrs.yr + dst_rule.eddtpart)
end
else (datepart(dw, yrs.yr + dst_rule.eddtpart) - 1) * -1
end as eddowref,
datename(dw, yrs.yr + dst_rule.stdtpart) as stdow,
datename(dw, yrs.yr + dst_rule.eddtpart) as eddow,
case
when dst_rule.strule in ('1', '2', '3')
then (7 * CAST(dst_rule.strule AS Integer)) - 7
else 0
end as stweekadd,
case
when dst_rule.edrule in ('1', '2', '3')
then (7 * CAST(dst_rule.edrule AS Integer)) - 7
else 0
end as edweekadd
from (
select '1900' yr
union select '1901' yr
union select '1902' yr
union select '1903' yr
union select '1904' yr
union select '1905' yr
union select '1906' yr
union select '1907' yr
union select '1908' yr
union select '1909' yr
union select '1910' yr
union select '1911' yr
union select '1912' yr
union select '1913' yr
union select '1914' yr
union select '1915' yr
union select '1916' yr
union select '1917' yr
union select '1918' yr
union select '1919' yr
union select '1920' yr
union select '1921' yr
union select '1922' yr
union select '1923' yr
union select '1924' yr
union select '1925' yr
union select '1926' yr
union select '1927' yr
union select '1928' yr
union select '1929' yr
union select '1930' yr
union select '1931' yr
union select '1932' yr
union select '1933' yr
union select '1934' yr
union select '1935' yr
union select '1936' yr
union select '1937' yr
union select '1938' yr
union select '1939' yr
union select '1940' yr
union select '1941' yr
union select '1942' yr
union select '1943' yr
union select '1944' yr
union select '1945' yr
union select '1946' yr
union select '1947' yr
union select '1948' yr
union select '1949' yr
union select '1950' yr
union select '1951' yr
union select '1952' yr
union select '1953' yr
union select '1954' yr
union select '1955' yr
union select '1956' yr
union select '1957' yr
union select '1958' yr
union select '1959' yr
union select '1960' yr
union select '1961' yr
union select '1962' yr
union select '1963' yr
union select '1964' yr
union select '1965' yr
union select '1966' yr
union select '1967' yr
union select '1968' yr
union select '1969' yr
union select '1970' yr
union select '1971' yr
union select '1972' yr
union select '1973' yr
union select '1974' yr
union select '1975' yr
union select '1976' yr
union select '1977' yr
union select '1978' yr
union select '1979' yr
union select '1980' yr
union select '1981' yr
union select '1982' yr
union select '1983' yr
union select '1984' yr
union select '1985' yr
union select '1986' yr
union select '1987' yr
union select '1988' yr
union select '1989' yr
union select '1990' yr
union select '1991' yr
union select '1992' yr
union select '1993' yr
union select '1994' yr
union select '1995' yr
union select '1996' yr
union select '1997' yr
union select '1998' yr
union select '1999' yr
union select '2000' yr
union select '2001' yr
union select '2002' yr
union select '2003' yr
union select '2004' yr
union select '2005' yr
union select '2006' yr -- OLD US RULES
union select '2007' yr
union select '2008' yr
union select '2009' yr
union select '2010' yr
union select '2011' yr
union select '2012' yr
union select '2013' yr
union select '2014' yr
union select '2015' yr
union select '2016' yr
union select '2017' yr
union select '2018' yr
union select '2018' yr
union select '2020' yr
union select '2021' yr
union select '2022' yr
union select '2023' yr
union select '2024' yr
union select '2025' yr
union select '2026' yr
union select '2027' yr
union select '2028' yr
union select '2029' yr
union select '2030' yr
union select '2031' yr
union select '2032' yr
union select '2033' yr
union select '2034' yr
union select '2035' yr
union select '2036' yr
union select '2037' yr
union select '2038' yr
union select '2039' yr
union select '2040' yr
union select '2041' yr
union select '2042' yr
union select '2043' yr
union select '2044' yr
union select '2045' yr
union select '2046' yr
union select '2047' yr
union select '2048' yr
union select '2049' yr
union select '2050' yr
union select '2051' yr
union select '2052' yr
union select '2053' yr
union select '2054' yr
union select '2055' yr
union select '2056' yr
union select '2057' yr
union select '2058' yr
union select '2059' yr
union select '2060' yr
union select '2061' yr
union select '2062' yr
union select '2063' yr
union select '2064' yr
union select '2065' yr
union select '2066' yr
union select '2067' yr
union select '2068' yr
union select '2069' yr
union select '2070' yr
union select '2071' yr
union select '2072' yr
union select '2073' yr
union select '2074' yr
union select '2075' yr
union select '2076' yr
union select '2077' yr
union select '2078' yr
union select '2079' yr
union select '2080' yr
union select '2081' yr
union select '2082' yr
union select '2083' yr
union select '2084' yr
union select '2085' yr
union select '2086' yr
union select '2087' yr
union select '2088' yr
union select '2089' yr
union select '2090' yr
union select '2091' yr
union select '2092' yr
union select '2093' yr
union select '2094' yr
union select '2095' yr
union select '2096' yr
union select '2097' yr
union select '2098' yr
union select '2099' yr
) yrs
cross join (
-- Dynamic, hardcoded table of timezone-based, daylight savings time (DST) rules
-- -- TIMEZONE
select 'UTC' zone, '+00:00' standard, '+01:00' daylight, 'UTC' rulename -- UTC - STAGING ONLY - this line is not accurate
union select 'CET' zone, '+01:00' standard, '+02:00' daylight, 'EU' rulename -- Centeral Europe
union select 'ET' zone, '-05:00' standard, '-04:00' daylight, 'US' rulename -- Eastern Time
union select 'CT' zone, '-06:00' standard, '-05:00' daylight, 'US' rulename -- Central Time
union select 'MT' zone, '-07:00' standard, '-06:00' daylight, 'US' rulename -- Mountain Time
union select 'PT' zone, '-08:00' standard, '-07:00' daylight, 'US' rulename -- Pacific Time
) timezone
join (
-- Dynamic, hardcoded table of country-based, daylight savings time (DST) rules
select 'UTC' rulename, 'L' strule, '-03-31' stdtpart, 'L' edrule, '-10-31' eddtpart, 1900 firstyr, 2099 lastyr, '01:00:00' cngtime
-- Country - Europe
union select 'EU' rulename, 'L' strule, '-03-31' stdtpart, 'L' edrule, '-10-31' eddtpart, 1900 firstyr, 2099 lastyr, '01:00:00' cngtime
-- Country - US
union select 'US' rulename, '1' strule, '-04-01' stdtpart, 'L' edrule, '-10-31' eddtpart, 1900 firstyr, 2006 lastyr, '02:00:00' cngtime
union select 'US' rulename, '2' strule, '-03-01' stdtpart, '1' edrule, '-11-01' eddtpart, 2007 firstyr, 2099 lastyr, '02:00:00' cngtime
) dst_rule on
dst_rule.rulename = timezone.rulename and
datepart( year, yrs.yr ) between firstyr and lastyr
) dst_dates
go
答案 2 :(得分：0)
我使用以下命令将当地的东部时间转换为UTC（因此函数中的固定值为4和5）。如果您具有2007年前的值，则实际上您需要修改下面的udf_IsInDST来适应该值。
CREATE FUNCTION [dbo].[udf_ConvertTimeLocalToUTC](@dt DATETIME)
RETURNS DATETIME
AS
BEGIN
SET @dt = DATEADD(HOUR, CASE WHEN [dbo].udf_IsInDST(@dt) = 1 THEN 4 ELSE 5 END, @dt)
RETURN @dt
END
GO
CREATE FUNCTION [dbo].[udf_IsInDST](@dt DATETIME)
RETURNS BIT
AS
BEGIN
DECLARE @returnValue BIT = 0
DECLARE @mm INT = DATEPART(MONTH, @dt)
DECLARE @dd INT = DATEPART(DAY, @dt)
DECLARE @dow INT = DATEPART(dw, @dt) -- 1 = sun
DECLARE @hr INT = DATEPART(HOUR, @dt)
SET @returnValue =
CASE WHEN @mm > 3 AND @mm < 11 THEN 1
WHEN @mm = 3 THEN
CASE WHEN @dd < 8 THEN 0
WHEN @dd >= 8 AND @dd <= 14 THEN (CASE WHEN @dow = 1 THEN (CASE WHEN @hr >= 2 THEN 1 ELSE 0 END) ELSE (CASE WHEN @dd - @dow >= 7 THEN 1 ELSE 0 END) END)
ELSE 1
END
WHEN @mm = 11 THEN
CASE WHEN @dd < 7 THEN (CASE WHEN @dow = 1 THEN (CASE WHEN @hr < 2 THEN 1 ELSE 0 END) ELSE (CASE WHEN @dow > @dd THEN 1 ELSE 0 END) END)
ELSE 0
END
ELSE 0
END;
RETURN @returnValue
END
GO
答案 3 :(得分：0)
我过去使用过2种方法。 首先是创建一个.Net CLR，该日期时间和时区为日期时间，并返回与数据一起存储的UTC日期时间值。 第二种解决方案仅需要在有限的时区中工作，并且涉及创建一个表，该表由时区ID，日期从，日期到以及过去和未来20年的日期的正确UTC偏移组成。从那里很容易加入并应用正确的偏移量。