I'm doing a few SQL select queries and would like to convert my UTC datetime column into local time to be displayed as local time in my query results. Note, I am NOT looking to do this conversion via code but rather when I am doing manual and random SQL queries against my databases.
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问题:
回答1:
You can do this as follows on SQL Server 2008 or greater:
SELECT CONVERT(datetime,
SWITCHOFFSET(CONVERT(datetimeoffset,
MyTable.UtcColumn),
DATENAME(TzOffset, SYSDATETIMEOFFSET())))
AS ColumnInLocalTime
FROM MyTable
You can also do the less verbose:
SELECT DATEADD(mi, DATEDIFF(mi, GETUTCDATE(), GETDATE()), MyTable.UtcColumn)
AS ColumnInLocalTime
FROM MyTable
Whatever you do, do not use - to subtract dates, because the operation is not atomic, and you will on occasion get indeterminate results due to race conditions between the system datetime and the local datetime being checked at different times (i.e., non-atomically).
Please note that this answer does not take DST into account. If you want to include a DST adjustment, please also see the following SO question:
How to create Daylight Savings time Start and End function in SQL Server
回答2:
I didn't find any of these example helpful in getting a datetime stored as UTC to a datetime in a specified timezone (NOT the timezone of the server because Azure SQL databases run as UTC). This is how I handled it. It's not elegant but it's simple and gives you the right answer without maintaining other tables:
select CONVERT(datetime, SWITCHOFFSET(dateTimeField, DATEPART(TZOFFSET,
dateTimeField AT TIME ZONE 'Eastern Standard Time')))
回答3:
If you need a conversion other than your server's location, here is a function that allows you to pass a standard offset and accounts for US Daylight Savings Times:
-- =============================================
-- Author: Ron Smith
-- Create date: 2013-10-23
-- Description: Converts UTC to DST
-- based on passed Standard offset
-- =============================================
CREATE FUNCTION [dbo].[fn_UTC_to_DST]
(
@UTC datetime,
@StandardOffset int
)
RETURNS datetime
AS
BEGIN
declare
@DST datetime,
@SSM datetime, -- Second Sunday in March
@FSN datetime -- First Sunday in November
-- get DST Range
set @SSM = datename(year,@UTC) + '0314'
set @SSM = dateadd(hour,2,dateadd(day,datepart(dw,@SSM)*-1+1,@SSM))
set @FSN = datename(year,@UTC) + '1107'
set @FSN = dateadd(second,-1,dateadd(hour,2,dateadd(day,datepart(dw,@FSN)*-1+1,@FSN)))
-- add an hour to @StandardOffset if @UTC is in DST range
if @UTC between @SSM and @FSN
set @StandardOffset = @StandardOffset + 1
-- convert to DST
set @DST = dateadd(hour,@StandardOffset,@UTC)
-- return converted datetime
return @DST
END
GO
回答4:
Using new SQL Server 2016 opportunities:
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
But clr procedure works in 5 times faster :'-(
Pay attention that Offset for one TimeZone can change to winter or summer time. For example
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'
results:
2017-02-08 09:00:00.000 -05:00
2017-08-08 09:00:00.000 -04:00
You can't just add constant offset.
回答5:
If enabling CLR on your database is an option as well as using the sql server's timezone, it can be written in .Net quite easily.
public partial class UserDefinedFunctions
{
[Microsoft.SqlServer.Server.SqlFunction]
public static SqlDateTime fn_GetLocalFromUTC(SqlDateTime UTC)
{
if (UTC.IsNull)
return UTC;
return new SqlDateTime(UTC.Value.ToLocalTime());
}
}
A UTC datetime value goes in and the local datetime value relative to the server comes out. Null values return null.
回答6:
Here's a version that accounts for daylight savings, UTC offset, and is not locked into a particular year.
---------------------------------------------------------------------------------------------------
--Name: udfToLocalTime.sql
--Purpose: To convert UTC to local US time accounting for DST
--Author: Patrick Slesicki
--Date: 3/25/2014
--Notes: Works on SQL Server 2008R2 and later, maybe SQL Server 2008 as well.
-- Good only for US States observing the Energy Policy Act of 2005.
-- Function doesn't apply for years prior to 2007.
-- Function assumes that the 1st day of the week is Sunday.
--Tests:
-- SELECT dbo.udfToLocalTime('2014-03-09 9:00', DEFAULT)
-- SELECT dbo.udfToLocalTime('2014-03-09 10:00', DEFAULT)
-- SELECT dbo.udfToLocalTime('2014-11-02 8:00', DEFAULT)
-- SELECT dbo.udfToLocalTime('2014-11-02 9:00', DEFAULT)
---------------------------------------------------------------------------------------------------
ALTER FUNCTION udfToLocalTime
(
@UtcDateTime AS DATETIME
,@UtcOffset AS INT = -8 --PST
)
RETURNS DATETIME
AS
BEGIN
DECLARE
@PstDateTime AS DATETIME
,@Year AS CHAR(4)
,@DstStart AS DATETIME
,@DstEnd AS DATETIME
,@Mar1 AS DATETIME
,@Nov1 AS DATETIME
,@MarTime AS TIME
,@NovTime AS TIME
,@Mar1Day AS INT
,@Nov1Day AS INT
,@MarDiff AS INT
,@NovDiff AS INT
SELECT
@Year = YEAR(@UtcDateTime)
,@MarTime = CONVERT(TIME, DATEADD(HOUR, -@UtcOffset, '1900-01-01 02:00'))
,@NovTime = CONVERT(TIME, DATEADD(HOUR, -@UtcOffset - 1, '1900-01-01 02:00'))
,@Mar1 = CONVERT(CHAR(16), @Year + '-03-01 ' + CONVERT(CHAR(5), @MarTime), 126)
,@Nov1 = CONVERT(CHAR(16), @Year + '-11-01 ' + CONVERT(CHAR(5), @NovTime), 126)
,@Mar1Day = DATEPART(WEEKDAY, @Mar1)
,@Nov1Day = DATEPART(WEEKDAY, @Nov1)
--Get number of days between Mar 1 and DST start date
IF @Mar1Day = 1 SET @MarDiff = 7
ELSE SET @MarDiff = 15 - @Mar1Day
--Get number of days between Nov 1 and DST end date
IF @Nov1Day = 1 SET @NovDiff = 0
ELSE SET @NovDiff = 8 - @Nov1Day
--Get DST start and end dates
SELECT
@DstStart = DATEADD(DAY, @MarDiff, @Mar1)
,@DstEnd = DATEADD(DAY, @NovDiff, @Nov1)
--Change UTC offset if @UtcDateTime is in DST Range
IF @UtcDateTime >= @DstStart AND @UtcDateTime < @DstEnd SET @UtcOffset = @UtcOffset + 1
--Get Conversion
SET @PstDateTime = DATEADD(HOUR, @UtcOffset, @UtcDateTime)
RETURN @PstDateTime
END
GO
回答7:
There is no simple way to do this in a correct AND generic way.
First of all it must be understood that the offset depends on the date in question, the Time Zone AND DST.
GetDate()-GetUTCDate only gives you the offset today at the server's TZ, which is not relevant.
I have seen only two working solution and I have search a lot.
1) A custom SQL function with a a couple of tables of base data such as Time Zones and DST rules per TZ. Working but not very elegant. I can't post it since I don't own the code.
EDIT: Here is an example of this method https://gist.github.com/drumsta/16b79cee6bc195cd89c8
2) Add a .net assembly to the db, .Net can do this very easily. This is working very well but the downside is that you need to configure several parameters on server level and the config is easily broken e.g. if you restore the database. I use this method but I cant post it since I don't own the code.
回答8:
I found the one off function way to be too slow when there is a lot of data. So I did it through joining to a table function that would allow for a calculation of the hour diff. It is basically datetime segments with the hour offset. A year would be 4 rows. So the table function
dbo.fn_getTimeZoneOffsets('3/1/2007 7:00am', '11/5/2007 9:00am', 'EPT')
would return this table:
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
It does account for daylight savings. A sample of how it is uses is below and the full blog post is here.
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
回答9:
declare @mydate2 datetime
set @mydate2=Getdate()
select @mydate2 as mydate,
dateadd(minute, datediff(minute,getdate(),@mydate2),getutcdate())
回答10:
None of these worked for me but this below worked 100%. Hope this can help others trying to convert it like I was.
CREATE FUNCTION [dbo].[fn_UTC_to_EST]
(
@UTC datetime,
@StandardOffset int
)
RETURNS datetime
AS
BEGIN
declare
@DST datetime,
@SSM datetime, -- Second Sunday in March
@FSN datetime -- First Sunday in November
-- get DST Range
set @SSM = DATEADD(dd,7 + (6-(DATEDIFF(dd,0,DATEADD(mm,(YEAR(GETDATE())-1900) * 12 + 2,0))%7)),DATEADD(mm,(YEAR(GETDATE())-1900) * 12 + 2,0))+'02:00:00'
set @FSN = DATEADD(dd, (6-(DATEDIFF(dd,0,DATEADD(mm,(YEAR(GETDATE())-1900) * 12 + 10,0))%7)),DATEADD(mm,(YEAR(GETDATE())-1900) * 12 + 10,0)) +'02:00:00'
-- add an hour to @StandardOffset if @UTC is in DST range
if @UTC between @SSM and @FSN
set @StandardOffset = @StandardOffset + 1
-- convert to DST
set @DST = dateadd(hour,@StandardOffset,@UTC)
-- return converted datetime
return @DST
END
回答11:
Ron's answer contains an error. It uses 2:00 AM local time where the UTC equivalent is required. I don't have enough reputation points to comment on Ron's answer so a corrected version appears below:
-- =============================================
-- Author: Ron Smith
-- Create date: 2013-10-23
-- Description: Converts UTC to DST
-- based on passed Standard offset
-- =============================================
CREATE FUNCTION [dbo].[fn_UTC_to_DST]
(
@UTC datetime,
@StandardOffset int
)
RETURNS datetime
AS
BEGIN
declare
@DST datetime,
@SSM datetime, -- Second Sunday in March
@FSN datetime -- First Sunday in November
-- get DST Range
set @SSM = datename(year,@UTC) + '0314'
set @SSM = dateadd(hour,2 - @StandardOffset,dateadd(day,datepart(dw,@SSM)*-1+1,@SSM))
set @FSN = datename(year,@UTC) + '1107'
set @FSN = dateadd(second,-1,dateadd(hour,2 - (@StandardOffset + 1),dateadd(day,datepart(dw,@FSN)*-1+1,@FSN)))
-- add an hour to @StandardOffset if @UTC is in DST range
if @UTC between @SSM and @FSN
set @StandardOffset = @StandardOffset + 1
-- convert to DST
set @DST = dateadd(hour,@StandardOffset,@UTC)
-- return converted datetime
return @DST
END
回答12:
The UNIX timestamp is merely the number of seconds between a particular date and the Unix Epoch,
SELECT DATEDIFF(SECOND,{d '1970-01-01'},GETDATE()) // This Will Return the UNIX timestamp In SQL server
you can create a function for local date time to Unix UTC conversion using Country Offset Function to Unix Time Stamp In SQL server
回答13:
As a warning - if you're going to use the following (note the milliseconds instead of minutes):
SELECT DATEADD(ms, DATEDIFF(ms, GETUTCDATE(), GETDATE()), MyTable.UtcColumn)
AS ColumnInLocalTime
FROM MyTable
Keep in mind that the DATEDIFF part will not always return the same number. So don't use it to compare DateTimes down to milliseconds.
回答14:
I've found that this function is faster than other solutions using a separate table or loops. It's just a basic case statement. Given that all months between April and October have a -4-hour offset (Eastern Time) we just need to add a few more case lines for the fringe days. Otherwise, the offset is -5 hours.
This is specific to a conversion from UTC to Eastern time, but additional time zone functions can be added as needed.
USE [YourDatabaseName]
GO
/****** Object: UserDefinedFunction [dbo].[ConvertUTCtoEastern] Script Date: 11/2/2016 5:21:52 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE FUNCTION [dbo].[ConvertUTCtoEastern]
(
@dtStartDate DATETIME
)
RETURNS DATETIME
AS
BEGIN
DECLARE @Working DATETIME
DECLARE @Returned DATETIME
SET @Working = @dtStartDate
SET @Working =
case when month(@Working) between 4 and 10 then dateadd(HH,-4,@Working)
when @Working between '2017-03-12' and '2017-11-05' then dateadd(HH,-4,@Working)
when @Working between '2016-03-13' and '2016-11-06' then dateadd(HH,-4,@Working)
when @Working between '2015-03-08' and '2015-11-01' then dateadd(HH,-4,@Working)
when @Working between '2014-03-09' and '2014-11-02' then dateadd(HH,-4,@Working)
when @Working between '2013-03-10' and '2013-11-03' then dateadd(HH,-4,@Working)
when @Working between '2012-03-11' and '2012-11-04' then dateadd(HH,-4,@Working)
else dateadd(HH,-5,@Working) end
SET @Returned = @Working
RETURN @Returned
END
GO
回答15:
This should be able to get server time with DST
declare @dt datetime
set @dt = getutcdate() -- GMT equivalent
sysdatetimeoffset takes DST into account
select [InputTime] = @dt
, [LocalTime2] = dateadd(mi, datediff(mi, sysdatetimeoffset(),getdate()), @dt)
回答16:
First function: configured for italian time zone (+1, +2), switch dates: last sunday of march and october, return the difference between the current time zone and the datetime as parameter.
Returns:
current timezone < parameter timezone ==> +1
current timezone > parameter timezone ==> -1
else 0
The code is:
CREATE FUNCTION [dbo].[UF_ADJUST_OFFSET]
(
@dt_utc datetime2(7)
)
RETURNS INT
AS
BEGIN
declare @month int,
@year int,
@current_offset int,
@offset_since int,
@offset int,
@yearmonth varchar(8),
@changeoffsetdate datetime2(7)
declare @lastweek table(giorno datetime2(7))
select @current_offset = DATEDIFF(hh, GETUTCDATE(), GETDATE())
select @month = datepart(month, @dt_utc)
if @month < 3 or @month > 10 Begin Set @offset_since = 1 Goto JMP End
if @month > 3 and @month < 10 Begin Set @offset_since = 2 Goto JMP End
--If i'm here is march or october
select @year = datepart(yyyy, @dt_utc)
if @month = 3
Begin
Set @yearmonth = cast(@year as varchar) + '-03-'
Insert Into @lastweek Values(@yearmonth + '31 03:00:00.000000'),(@yearmonth + '30 03:00:00.000000'),(@yearmonth + '29 03:00:00.000000'),(@yearmonth + '28 03:00:00.000000'),
(@yearmonth + '27 03:00:00.000000'),(@yearmonth + '26 03:00:00.000000'),(@yearmonth + '25 03:00:00.000000')
--Last week of march
Select @changeoffsetdate = giorno From @lastweek Where datepart(weekday, giorno) = 1
if @dt_utc < @changeoffsetdate
Begin
Set @offset_since = 1
End Else Begin
Set @offset_since = 2
End
End
if @month = 10
Begin
Set @yearmonth = cast(@year as varchar) + '-10-'
Insert Into @lastweek Values(@yearmonth + '31 03:00:00.000000'),(@yearmonth + '30 03:00:00.000000'),(@yearmonth + '29 03:00:00.000000'),(@yearmonth + '28 03:00:00.000000'),
(@yearmonth + '27 03:00:00.000000'),(@yearmonth + '26 03:00:00.000000'),(@yearmonth + '25 03:00:00.000000')
--Last week of october
Select @changeoffsetdate = giorno From @lastweek Where datepart(weekday, giorno) = 1
if @dt_utc > @changeoffsetdate
Begin
Set @offset_since = 1
End Else Begin
Set @offset_since = 2
End
End
JMP:
if @current_offset < @offset_since Begin
Set @offset = 1
End Else if @current_offset > @offset_since Set @offset = -1 Else Set @offset = 0
Return @offset
END
Then the function that convert date
CREATE FUNCTION [dbo].[UF_CONVERT]
(
@dt_utc datetime2(7)
)
RETURNS datetime
AS
BEGIN
declare @offset int
Select @offset = dbo.UF_ADJUST_OFFSET(@dt_utc)
if @dt_utc >= '9999-12-31 22:59:59.9999999'
set @dt_utc = '9999-12-31 23:59:59.9999999'
Else
set @dt_utc = (SELECT DATEADD(mi, DATEDIFF(mi, GETUTCDATE(), GETDATE()), @dt_utc) )
if @offset <> 0
Set @dt_utc = dateadd(hh, @offset, @dt_utc)
RETURN @dt_utc
END
回答17:
It's simple. Try this for Azure SQL Server:
SELECT YourDateTimeColumn AT TIME ZONE 'Eastern Standard Time' FROM YourTable
For Local SQL Server :
SELECT CONVERT(datetime2, SWITCHOFFSET(CONVERT(datetimeoffset, gETDATE()), DATENAME(TzOffset, gETDATE() AT TIME ZONE 'Eastern Standard Time'))) FROM YourTable
回答18:
-- get indian standard time from utc
CREATE FUNCTION dbo.getISTTime
(
@UTCDate datetime
)
RETURNS datetime
AS
BEGIN
RETURN dateadd(minute,330,@UTCDate)
END
GO
回答19:
Here's a simpler one that takes dst in to account
CREATE FUNCTION [dbo].[UtcToLocal]
(
@p_utcDatetime DATETIME
)
RETURNS DATETIME
AS
BEGIN
RETURN DATEADD(MINUTE, DATEDIFF(MINUTE, GETUTCDATE(), @p_utcDatetime), GETDATE())
END
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