DateTime差异 - SQL

Question

我试图获取两个DateTime值之间的DateTime差异.

查询我到目前为止,

DECLARE @start datetime = '2012-01-01 12:00:00.000'
DECLARE @end datetime =  '2013-01-01 11:59:59.999'

SELECT 
      CONVERT(VARCHAR(5),DATEDIFF(YYYY, @start, @end))
+'-'+ CONVERT(VARCHAR(5),DATEDIFF(MONTH, @start, @end))
+'-'+ CONVERT(VARCHAR(5),DATEDIFF(SECOND, @start, @end)/86400)
+' '+ CONVERT(VARCHAR(5),DATEDIFF(SECOND, @start, @end)%86400/3600)
+':'+ CONVERT(VARCHAR(5),DATEDIFF(SECOND, @start, @end)%3600/60)
+':'+ CONVERT(VARCHAR(5),(DATEDIFF(SECOND, @start, @end)%60)) 
+'.'+ CONVERT(VARCHAR(5),(DATEDIFF(SECOND, @start, @end)%100))
AS [YYYY-MM-DD HH:MM:SS.MSS]

期望的输出

0001-00-00 23:59:59.999
365 Days, 23 Hours, 59 Minutes, 59 Seconds, 999 Milliseconds

实际产出

1-12-366 8784:0:0.0

谢谢

Answer 1

日期时间精度四舍五入为.000,.003或.007秒的增量.为了更好的准确性,请使用 DateTime2数据类型.

DECLARE @start datetime2 = '2012-01-01 12:00:00.000'
DECLARE @end datetime2 =  '2013-01-01 11:59:59.999'

--I do this way because millisecond difference overflows the integer.
select datediff(day, @start, @end) days,
       datediff(millisecond, convert(time, @start), convert(time, @end)) milliseconds

结果和小提琴演示:

   days | milliseconds
   366  | -1

以上结果意味着您可以获得所需的结果:

  (366 days - 1 millisecond) =  
   365 Days, 23 Hours, 59 Minutes, 59 Seconds, 999 Milliseconds

编辑:请注意,给定的两个日期之间的毫秒差异太高,实际上溢出bigint也是如此.所以我使用这种方法 来得到你期望的答案.