sql-server - 夏時間がオンかオフかを確認します

Question

シナリオでは、夏時間が有効になっているかどうかを確認する必要があります。チェックの結果に基づいて、SQLサーバープロシージャでいくつかの計算を行う必要があります。

夏時間が現在有効になっているかどうかをすばやく確認するための最良の方法は何ですか？

Answer 1

I used this Daylight Savings Time Functions in SQL Server that is created by Tim Cullen.

Specifically, the code that I used was:

Start Date Function

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

End Date Function

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

I then use the functions like this in my query:

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