如果你的本地日期时间是东部标准时间，你想从UTC转换为UTC，那么在Azure SQL和SQL Server 2016及以上版本中，你可以这样做:

SELECT YourUtcColumn AT TIME ZONE 'UTC' AT TIME ZONE 'Eastern Standard Time' AS
       LocalTime
FROM   YourTable

时区名称的完整列表可以在以下地址找到:

SELECT * FROM sys.time_zone_info 

是的，时区的命名很糟糕——即使是东部标准时间，也考虑到了夏令时。

这可以在没有函数的情况下完成。下面的代码将把UTC时间转换为考虑夏令时的山地时间。相应地调整所有的-6和-7数字到您的时区(即对于EST，您将分别调整为-4和-5)

--Adjust a UTC value, in the example the UTC field is identified as UTC.Field, to account for daylight savings time when converting out of UTC to Mountain time.
CASE
    --When it's between March and November, it is summer time which is -6 from UTC
    WHEN MONTH ( UTC.Field ) > 3 AND MONTH ( UTC.Field ) < 11 
        THEN DATEADD ( HOUR , -6 , UTC.Field )
    --When its March and the day is greater than the 14, you know it's summer (-6)
    WHEN MONTH ( UTC.Field ) = 3
        AND DATEPART ( DAY , UTC.Field ) >= 14 
        THEN
            --However, if UTC is before 9am on that Sunday, then it's before 2am Mountain which means it's still Winter daylight time.
            CASE 
                WHEN DATEPART ( WEEKDAY , UTC.Field ) = 1 
                    AND UTC.Field < '9:00'
                    --Before 2am mountain time so it's winter, -7 hours for Winter daylight time
                    THEN DATEADD ( HOUR , -7 , UTC.Field )
                --Otherwise -6 because it'll be after 2am making it Summer daylight time
                ELSE DATEADD ( HOUR , -6 , UTC.Field )
            END
    WHEN MONTH ( UTC.Field ) = 3
        AND ( DATEPART ( WEEKDAY , UTC.Field ) + 7 ) <= DATEPART ( day , UTC.Field ) 
        THEN 
            --According to the date, it's moved onto Summer daylight, but we need to account for the hours leading up to 2am if it's Sunday
            CASE 
                WHEN DATEPART ( WEEKDAY , UTC.Field ) = 1 
                    AND UTC.Field < '9:00'
                    --Before 9am UTC is before 2am Mountain so it's winter Daylight, -7 hours
                    THEN DATEADD ( HOUR , -7 , UTC.Field )
                --Otherwise, it's summer daylight, -6 hours
                ELSE DATEADD ( HOUR , -6 , UTC.Field )
            END
    --When it's November and the weekday is greater than the calendar date, it's still Summer so -6 from the time
    WHEN MONTH ( UTC.Field ) = 11
        AND DATEPART ( WEEKDAY , UTC.Field ) > DATEPART ( DAY , UTC.Field ) 
        THEN DATEADD ( HOUR , -6 , UTC.Field )
    WHEN MONTH ( UTC.Field ) = 11
        AND DATEPART ( WEEKDAY , UTC.Field ) <= DATEPART ( DAY , UTC.Field ) 
            --If the weekday is less than or equal to the calendar day it's Winter daylight but we need to account for the hours leading up to 2am.
            CASE 
                WHEN DATEPART ( WEEKDAY , UTC.Field ) = 1 
                    AND UTC.Field < '8:00'
                    --If it's before 8am UTC and it's Sunday in the logic outlined, then it's still Summer daylight, -6 hours
                    THEN DATEADD ( HOUR , -6 , UTC.Field )
                --Otherwise, adjust for Winter daylight at -7
                ELSE DATEADD ( HOUR , -7 , UTC.Field )
            END
    --If the date doesn't fall into any of the above logic, it's Winter daylight, -7
    ELSE
        DATEADD ( HOUR , -7 , UTC.Field )
END

我有代码执行UTC到本地和本地到UTC时间，允许使用这样的代码进行转换

DECLARE @usersTimezone VARCHAR(32)='Europe/London'
DECLARE @utcDT DATETIME=GetUTCDate()
DECLARE @userDT DATETIME=[dbo].[funcUTCtoLocal](@utcDT, @usersTimezone)

and

DECLARE @usersTimezone VARCHAR(32)='Europe/London'
DECLARE @userDT DATETIME=GetDate()
DECLARE @utcDT DATETIME=[dbo].[funcLocaltoUTC](@userDT, @usersTimezone)

这些函数可以支持NodaTime提供的IANA/TZDB中的全部或一部分时区-请参阅https://nodatime.org/TimeZones上的完整列表

请注意，我的用例意味着我只需要一个“当前”窗口，允许在大约+/- 5年的范围内转换时间。这意味着，如果您需要很宽的时间段，我使用的方法可能不适合您，因为它在给定日期范围内为每个时区间隔生成代码的方式不同。

该项目位于GitHub: https://github.com/elliveny/SQLServerTimeConversion

这将生成如下示例所示的SQL函数代码

对于任何仍然试图解决这个问题的人，这里有一个在SQL Server 2017中工作的概念证明

 declare
    @StartDate date = '2020-01-01'

;with cte_utc as
(
    select 
         1 as i
        ,CONVERT(datetime, @StartDate) AS UTC
        ,datepart(weekday, CONVERT(datetime, @StartDate)) as Weekday
        ,datepart(month, CONVERT(datetime, @StartDate)) as [Month]
        ,datepart(YEAR, CONVERT(datetime, @StartDate)) as [Year]
        
    union all

    Select
         i + 1
        ,dateadd(d, 1, utc)
        ,datepart(weekday, CONVERT(datetime, dateadd(d, 1, utc))) as Weekday
        ,datepart(month, CONVERT(datetime, dateadd(d, 1, utc))) as [Month]
        ,datepart(YEAR, CONVERT(datetime, dateadd(d, 1, utc))) as [Year]
    from    
        cte_utc
    where
        (i + 1) < 32767

), cte_utc_dates as 
(
    select 
        *,
        DENSE_RANK()OVER(PARTITION BY [Year], [Month], [Weekday] ORDER BY Utc) WeekDayIndex
    from
        cte_utc

), cte_hours as (
    select 0 as [Hour]
    union all
    select [Hour] + 1 from cte_hours where [Hour] < 23
)

select
    d.*
    , DATEADD(hour, h.Hour, d.UTC) AS UtcTime
    ,CONVERT(datetime, DATEADD(hour, h.Hour, d.UTC) AT TIME ZONE 'UTC' AT TIME ZONE 'Central Standard Time') CST
    ,CONVERT(datetime, DATEADD(hour, h.Hour, d.UTC) AT TIME ZONE 'UTC' AT TIME ZONE 'Eastern Standard Time') EST
from
    cte_utc_dates d, cte_hours h
where
    ([Month] = 3 and [Weekday] = 1 and WeekDayIndex = 2 )-- dst start
    or 
    ([Month] = 11 and [Weekday] = 1 and WeekDayIndex = 1 )-- dst end
order by
    utc
OPTION (MAXRECURSION 32767)

GO

你可以在SQL Server 2008或更高版本上这样做:

SELECT CONVERT(datetime, 
               SWITCHOFFSET(CONVERT(datetimeoffset, 
                                    MyTable.UtcColumn), 
                            DATENAME(TzOffset, SYSDATETIMEOFFSET()))) 
       AS ColumnInLocalTime
FROM MyTable

你也可以用更简洁的方法:

SELECT DATEADD(mi, DATEDIFF(mi, GETUTCDATE(), GETDATE()), MyTable.UtcColumn) 
       AS ColumnInLocalTime
FROM MyTable

无论您做什么，都不要使用-来减去日期，因为该操作不是原子的，并且由于在不同时间(即非原子地)检查的系统datetime和本地datetime之间的竞争条件，您有时会得到不确定的结果。

请注意，这个答案没有考虑夏令时。如果你想包含夏令时调整，也请参阅以下SO问题:

如何在SQL Server中创建夏令时开始和结束函数

我发现当有大量数据时，一次性函数的方法太慢了。因此，我通过连接到一个允许计算小时差的表函数来实现它，它基本上是带有小时偏移量的datetime分段。一年是4行。这个表格函数

dbo.fn_getTimeZoneOffsets('3/1/2007 7:00am', '11/5/2007 9:00am', 'EPT')

将返回这个表:

startTime          endTime   offset  isHr2
3/1/07 7:00     3/11/07 6:59    -5    0
3/11/07 7:00    11/4/07 6:59    -4    0
11/4/07 7:00    11/4/07 7:59    -5    1
11/4/07 8:00    11/5/07 9:00    -5    0

它确实考虑了夏时制。下面是它如何使用的示例，完整的博客文章在这里。

select mt.startTime as startUTC, 
    dateadd(hh, tzStart.offset, mt.startTime) as startLocal, 
    tzStart.isHr2
from MyTable mt 
inner join dbo.fn_getTimeZoneOffsets(@startViewUTC, @endViewUTC, @timeZone)  tzStart
on mt.startTime between tzStart.startTime and tzStart.endTime