Tsql 如何在T-SQL中将DATETIME转换为FILETIME值?
我需要在T-SQLSELECT语句(在SQL Server 2000上)中将SQL ServerDATETIME值转换为FILETIME。是否有内置的功能来执行此操作?如果没有,有人能帮我弄清楚如何将此转换例程实现为UDF(或纯Transact-SQL)?以下是我所知道的:Tsql 如何在T-SQL中将DATETIME转换为FILETIME值?,tsql,datetime,filetime,Tsql,Datetime,Filetime,我需要在T-SQLSELECT语句(在SQL Server 2000上)中将SQL ServerDATETIME值转换为FILETIME。是否有内置的功能来执行此操作?如果没有,有人能帮我弄清楚如何将此转换例程实现为UDF(或纯Transact-SQL)?以下是我所知道的: FILETIME是64位值,表示自 1601年1月1日(UTC)(per) SQL Server基准时间从1900-01-01 00:00:00开始(每次选择转换(0作为日期时间)) 我找到了几个示例,展示了如何将FILET
select cast('17800122' as datetime)
输出
1780-01-22 00:00:00.000
但是这仍然比文件时间短,所以您需要添加这一点……但是请记住格里高利历和儒略历(也是日期时间从1753年开始的原因)好的,我想我自己能够实现这一点。下面是函数:
IF EXISTS
(
SELECT 1
FROM sysobjects
WHERE id = OBJECT_ID('[dbo].[fnDateTimeToFileTime]')
AND type = 'FN'
)
BEGIN
DROP FUNCTION [dbo].[fnDateTimeToFileTime]
END
GO
-- Create function.
CREATE FUNCTION [dbo].[fnDateTimeToFileTime]
(
@DateTime AS DATETIME
)
RETURNS
BIGINT
BEGIN
IF @DateTime IS NULL
RETURN NULL
DECLARE @MsecBetween1601And1970 BIGINT
DECLARE @MsecBetween1970AndDate BIGINT
SET @MsecBetween1601And1970 = 11644473600000
SET @MsecBetween1970AndDate =
DATEDIFF(ss, CAST('1970-01-01 00:00:00' as DATETIME), @DateTime) *
CAST(1000 AS BIGINT)
RETURN (@MsecBetween1601And1970 + @MsecBetween1970AndDate) * CAST(10000 AS BIGINT)
END
GO
IF @@ERROR = 0
GRANT EXECUTE ON [dbo].[fnDateTimeToFileTime] TO Public
GO
它似乎精确到1秒,这对我来说还行(由于数据溢出,我无法使它更精确)。我使用计算日期之间的持续时间
你认为呢?接受的答案很有效,但会在2038年1月19日之后崩溃。使用 如果您使用的是SQL Server 2016或更高版本,请使用DATEDIFF_BIG而不是DATEDIFF,或者使用以下更正
CREATE FUNCTION [dbo].[fnDateTimeToFileTime]
(
@DateTime AS DATETIME
)
RETURNS
BIGINT
BEGIN
IF @DateTime IS NULL
RETURN NULL
DECLARE @MsecBetween1601And1970 BIGINT
DECLARE @MsecBetween1970AndDate BIGINT
DECLARE @MaxNumberDayBeforeOverflowDateDiff int;
SET @MaxNumberDayBeforeOverflowDateDiff = 24855; --SELECT DATEDIFF(day, CAST('1970-01-01 00:00:00' as DATETIME), CAST('2038-01-19 00:00:00' as DATETIME))
DECLARE @nbMaxDaysBetween1970AndDate int;
SET @nbMaxDaysBetween1970AndDate = DATEDIFF(day, CAST('1970-01-01 00:00:00' as DATETIME), @DateTime) / @MaxNumberDayBeforeOverflowDateDiff;
DECLARE @moduloResteDay int
SET @moduloResteDay = DATEDIFF(day, CAST('1970-01-01 00:00:00' as DATETIME), @DateTime) % @MaxNumberDayBeforeOverflowDateDiff;
DECLARE @nbSecondBefore19700101And20380119 bigint = 2147472000;
SET @MsecBetween1601And1970 = 11644473600000;
DECLARE @DateTimeModulo datetime;
SET @DateTimeModulo = DATEADD(day, -@nbMaxDaysBetween1970AndDate * @MaxNumberDayBeforeOverflowDateDiff, @DateTime)
SET @MsecBetween1970AndDate = CAST(CAST(@nbMaxDaysBetween1970AndDate as bigint) * @nbSecondBefore19700101And20380119 +
DATEDIFF(ss, CAST('1970-01-01 00:00:00' as DATETIME), @DateTimeModulo) as bigint)*
CAST(1000 AS BIGINT)
RETURN (@MsecBetween1601And1970 + @MsecBetween1970AndDate) * CAST(10000 AS BIGINT)
END
哦,太好了,现在我更困惑了。:-)至少在SQLServer2008DateTime2到了第一年