declare @mydate2 datetime
 set @mydate2=Getdate()
 select @mydate2 as mydate,
 dateadd(minute, datediff(minute,getdate(),@mydate2),getutcdate())

告诉服务器保存时间的时间，'utc'，然后要求它转换为特定的时区，在这种情况下是'巴西/东部'

quiz_step_progresses.created_at  at time zone 'utc' at time zone 'Brazil/East'

使用以下选择获取时区的完整列表;

select * from pg_timezone_names;

详情请点击这里。

https://popsql.com/learn-sql/postgresql/how-to-convert-utc-to-local-time-zone-in-postgresql

我发现这个函数比使用单独的表或循环的其他解决方案更快。这只是一个基本的case语句。考虑到4月到10月之间的所有月份都有-4小时的偏移(东部时间)，我们只需要为边缘日添加更多的案例线。否则，偏移量为-5小时。

这是特定于从UTC到东部时间的转换，但可以根据需要添加其他时区功能。

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

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

如果你需要一个转换而不是你的服务器位置，这里有一个函数，允许你传递一个标准偏移量，并考虑美国夏令时:

-- =============================================
-- 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

第一个功能:配置为意大利时区(+1，+2)，切换日期:3月和10月的最后一个星期天，返回当前时区与datetime的差值作为参数。

Returns:
current timezone < parameter timezone ==> +1
current timezone > parameter timezone ==> -1
else 0

代码是:

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

然后是转换日期的函数

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