asp.net - 在 SQL Server 上处理夏令时

Question

嗨，SQL Server 上是否有一个功能可以识别夏令时是否处于活动状态。

我在其中创建了一个标量函数，该函数将服务器时间转换为在执行插入/更新时使用应用程序的工厂位置时间。

问题是我不知道美国有夏令时。所以我的计划是我会做类似的事情

if DST is active
   // -1
else
  // + 1
end

我需要检查 DST 是否处于活动状态

有什么想法吗？

谢谢并恭祝安康

Answer 1

处理夏令时功能：

CREATE function [dbo].[fn_GetDaylightSavingsTimeStart]
(@Year varchar(4))
RETURNS smalldatetime
as
begin
declare @DTSStartWeek smalldatetime, @DTSEndWeek smalldatetime
set @DTSStartWeek = '03/01/' + convert(varchar,@Year)
return case datepart(dw,@DTSStartWeek)
when 1 then
dateadd(hour,170,@DTSStartWeek)
when 2 then
dateadd(hour,314,@DTSStartWeek)
when 3 then
dateadd(hour,290,@DTSStartWeek)
when 4 then
dateadd(hour,266,@DTSStartWeek)
when 5 then
dateadd(hour,242,@DTSStartWeek)
when 6 then
dateadd(hour,218,@DTSStartWeek)
when 7 then
dateadd(hour,194,@DTSStartWeek)
end
end

CREATE function [dbo].[fn_GetDaylightSavingsTimeEnd]
(@Year varchar(4))
RETURNS smalldatetime
as
begin
declare @DTSEndWeek smalldatetime
set @DTSEndWeek = '11/01/' + convert(varchar,@Year)
return case datepart(dw,dateadd(week,1,@DTSEndWeek))
when 1 then
dateadd(hour,2,@DTSEndWeek)
when 2 then
dateadd(hour,146,@DTSEndWeek)
when 3 then
dateadd(hour,122,@DTSEndWeek)
when 4 then
dateadd(hour,98,@DTSEndWeek)
when 5 then
dateadd(hour,74,@DTSEndWeek)
when 6 then
dateadd(hour,50,@DTSEndWeek)
when 7 then
dateadd(hour,26,@DTSEndWeek)
end
end

declare @DLSStart smalldatetime
, @DLSEnd smalldatetime
, @DLSActive tinyint
set @DLSStart = (select MSSQLTIPS.dbo.fn_GetDaylightSavingsTimeStart(convert(varchar,datepart(year,getdate()))))
set @DLSEnd = (select MSSQLTIPS.dbo.fn_GetDaylightSavingsTimeEnd(convert(varchar,datepart(year,getdate()))))    
if @Date between @DLSStart and @DLSEnd
begin
set @DLSActive = 1
end
else
begin
set @DLSActive = 0
end
select @DLSActive