DATETIME类型和BIGINT 类型互相转换

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:   GGA
-- Create date: 2013-03-28
-- Description: 将时间类型转化成BIGINT，返回指定时间
-- 到-01-01 08:00:00.000的毫秒数
-- =============================================
CREATE FUNCTION [dbo].[ufn_GetMSIntFormTime]
(
   @dt DATETIME
)
RETURNS BIGINT
AS
BEGIN
   -- Declare the return variable here
   DECLARE @dtInt BIGINT
 
   SELECT @dtInt=DATEDIFF(SECOND , '1970-01-01 08:00:00.000' , @dt ) --秒数
   set @dtInt = @dtInt*1000 + DATEPART(MILLISECOND,@dt) -- 毫秒数
   RETURN @dtInt
END
 
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:   GGA
-- Create date: 2013-03-28
-- Description: 根据毫秒数计算出时间
-- =============================================
CREATE FUNCTION [dbo].[ufn_GetTimeFormMSInt]
(
   @msINT BIGINT
)
RETURNS DATETIME
AS
  BEGIN
   DECLARE @secInt BIGINT
   DECLARE @leftMsInt BIGINT
  
   SET @secInt=@msINT/1000;
   SET @leftMsInt=@msINT%1000;
 
   DECLARE @date DATETIME
   SET @date = DATEADD(SECOND,@secInt,'1970-01-01 8:00:00:000')
   SET @date = DATEADD(MILLISECOND,@leftMsInt,@date)
   RETURN @date
 END
GO