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
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
其他回答
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;
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
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
这些对我来说都没用，但下面这个100%有效。希望这能帮助其他像我一样尝试转换它的人。
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
罗恩的回答有一个错误。它使用当地时间凌晨2:00，其中需要UTC等效值。我没有足够的声望分数来评论Ron的回答，所以更正版本如下:
-- =============================================
-- 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
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