我正在做一些SQL选择查询,并希望将我的UTC日期时间列转换为本地时间,以便在我的查询结果中显示为本地时间。注意,我不希望通过代码进行这种转换,而是当我对我的数据库进行手动和随机SQL查询时。
当前回答
使用新的SQL Server 2016机会:
CREATE FUNCTION ToLocalTime(@dtUtc datetime, @timezoneId nvarchar(256))
RETURNS datetime
AS BEGIN
return @dtUtc AT TIME ZONE 'UTC' AT TIME ZONE @timezoneId
/* -- second way, faster
return SWITCHOFFSET(@dtUtc , DATENAME(tz, @dtUtc AT TIME ZONE @timezoneId))
*/
/* -- third way
declare @dtLocal datetimeoffset
set @dtLocal = @dtUtc AT TIME ZONE @timezoneId
return dateadd(minute, DATEPART (TZoffset, @dtLocal), @dtUtc)
*/
END
GO
但clr程序的工作速度快5倍:'-(
请注意,一个时区的偏移量可以更改为冬季时间或夏季时间。例如
select cast('2017-02-08 09:00:00.000' as datetime) AT TIME ZONE 'Eastern Standard Time'
select cast('2017-08-08 09:00:00.000' as datetime) AT TIME ZONE 'Eastern Standard Time'
结果:
2017-02-08 09:00:00.000 -05:00
2017-08-08 09:00:00.000 -04:00
你不能只是添加常数偏移量。
其他回答
这样就可以获得与夏令时同步的服务器时间
declare @dt datetime
set @dt = getutcdate() -- GMT equivalent
sysdatetimeoffset会考虑夏令时
select [InputTime] = @dt
, [LocalTime2] = dateadd(mi, datediff(mi, sysdatetimeoffset(),getdate()), @dt)
您必须重新格式化字符串以及转换为正确的时间。在这种情况下,我需要祖鲁时间。
Declare @Date datetime;
Declare @DateString varchar(50);
set @Date = GETDATE();
declare @ZuluTime datetime;
Declare @DateFrom varchar (50);
Declare @DateTo varchar (50);
set @ZuluTime = DATEADD(second, DATEDIFF(second, GETDATE(), GETUTCDATE()), @Date);
set @DateString = FORMAT(@ZuluTime, 'yyyy-MM-ddThh:mm:ssZ', 'en-US' )
select @DateString;
对甲骨文来说最好的方法:
硬编码的datetime:
SELECT TO_CHAR(CAST((FROM_TZ(CAST(TO_DATE('2018-10-27 21:00', 'YYYY-MM-DD HH24:MI') AS TIMESTAMP), 'UTC') AT TIME ZONE 'EET') AS DATE), 'YYYY-MM-DD HH24:MI') UTC_TO_EET FROM DUAL
结果: 2018-10-28 00:00
列名和表名:
SELECT TO_CHAR(CAST((FROM_TZ(CAST(COLUMN_NAME AS TIMESTAMP), 'UTC') AT TIME ZONE 'EET') AS DATE), 'YYYY-MM-DD HH24:MI') UTC_TO_EET FROM TABLE_NAME
declare @mydate2 datetime
set @mydate2=Getdate()
select @mydate2 as mydate,
dateadd(minute, datediff(minute,getdate(),@mydate2),getutcdate())
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
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