sql 时间计算

---兩個時間之差的合計
DECLARE @I INT
SET @I = DATEDIFF(ms,GETDATE()-RAND()*24,GETDATE())
SELECT
   convert(varchar(10), @I/86400000) + ' Days  ' +
   convert(varchar(10), (@I%86400000)/3600000) + ' Hours  '+
   convert(varchar(10), (@I%3600000)/60000) + ' Mins  '+
   convert(varchar(10), (@I%60000)/1000) + ' sec ' +
   convert(varchar(10), @I%1000) + ' ms  ' AS [DD:HH:MM:SS:MS]

-- Find Hours, Minutes and Seconds in between two datetime
DECLARE @First datetime
DECLARE @Second datetime
SET @First = '04/02/2008 05:23:22'
SET @Second = getdate()

SELECT DATEDIFF(day,@First,@Second)*24 as TotalHours,
DATEDIFF(day,@First,@Second)*24*60 as TotalMinutes,
DATEDIFF(day,@First,@Second)*24*60*60 as TotalSeconds 


select DateDiff ('d','1999-05-01','1999-03-07')
/*
--Geovin Du 塗聚文 締友計算機信息技術有限公司
year   yy,   yyyy  
quarter   qq,   q  
Month   mm,   m  
dayofyear   dy,   y  
Day   dd,   d  
Week   wk,   ww  
Hour   hh  
minute   mi,   n  
second   ss,   s  
millisecond   ms  
*/

---分鍾化小時
DECLARE @strardate datetime,@enddate datetime,@hour int,@minute float
set @strardate='2011-08-15 18:00'
set @enddate='2011-08-15 22:45'
select @hour=DateDiff(hour,@strardate,@enddate)
select @minute=DateDiff(minute,@strardate,@enddate)%60
select @hour
select @hour+@minute/60
select @hour+round(@minute/60,1,1)---四舍五入


SELECT ROUND(150.75, 0);
GO
SELECT ROUND(150.75, 0, 1);
GO

select DateDiff(hh,@strardate,@enddate)
select DateDiff(mi,@strardate,@enddate)

declare @hms varchar(8)
set @hms = '10:30:00'
declare @hours int
declare @minutes decimal
set @hours = datepart(hour, @hms)
set @minutes = datepart(minute, @hms)
select @minutes/60+@hours
select round(@minutes/60,1)+@hours---四舍五入

---公司的加班計算，當大於半小時計加班半小時，不足半小時，不計加班
DECLARE @strardate datetime,@enddate datetime,@hour int,@minute float,@minutes float
set @strardate='2011-08-15 18:00'
set @enddate='2011-08-15 22:45'
select @hour=DateDiff(hour,@strardate,@enddate)
select @minute=DateDiff(minute,@strardate,@enddate)%60
--select @hour+round(@minute/60,1,1)
set @minutes=@minute/60
if @minutes>0.5
   set @minutes=0.5
if @minutes<0.5
   set @minutes=0
select @minutes
select @hour
--select @minute
select @hour+@minutes
---
select 
  sum(TotalSeconds) / 86400 as Days,
  (sum(TotalSeconds) % 86400) / 3600 as Hours, 
  (sum(TotalSeconds) % 3600) / 60 as Minutes, 
  sum(TotalSeconds) % 60 as Seconds
from
(
    select EventID, DateDiff(second, StartDate, EndDate) as TotalSeconds 
    from Events
) x