Difference of two date time in sql server

Question

Is there any way to take the difference between two datetime in sql server?

For example, my dates are

1. 2010-01-22 15:29:55.090

Answer 1

I tried this way and it worked. I used SQL Server version 2016

SELECT DATEDIFF(MILLISECOND,'2010-01-22 15:29:55.090', '2010-01-22 15:30:09.153')/1000.00;

Different DATEDIFF Functions are:

SELECT DATEDIFF(year,        '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(quarter,     '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(month,       '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(dayofyear,   '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(day,         '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(week,        '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(hour,        '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(minute,      '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(second,      '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');
SELECT DATEDIFF(millisecond, '2005-12-31 23:59:59.9999999', '2006-01-01 00:00:00.0000000');

Ref: https://docs.microsoft.com/en-us/sql/t-sql/functions/datediff-transact-sql?view=sql-server-2017

Answer 2

SELECT DATEDIFF(yyyy, '2011/08/25', '2017/08/25') AS DateDiff

It's gives you difference between two dates in Year

Here (2017-2011)=6 as a result

Syntax:

DATEDIFF(interval, date1, date2)

Answer 3

I can mention four important functions of MS SQL Server that can be very useful:

1) The function DATEDIFF() is responsible to calculate differences between two dates, the result could be "year quarter month dayofyear day week hour minute second millisecond microsecond nanosecond", specified on the first parameter (datepart):

select datediff(day,'1997-10-07','2011-09-11')

2) You can use the function GETDATE() to get the actual time and calculate differences of some date and actual date:

select datediff(day,'1997-10-07', getdate() )

3) Another important function is DATEADD(), used to convert some value in datetime using the same datepart of the datediff, that you can add (with positive values) or substract (with negative values) to one base date:

select DATEADD(day,  45, getdate()) -- actual datetime adding 45 days
select DATEADD(  s,-638, getdate()) -- actual datetime subtracting 10 minutes and 38 seconds

4) The function CONVERT() was made to format the date like you need, it is not parametric function, but you can use part of the result to format the result like you need:

select convert(  char(8), getdate() ,   8) -- part hh:mm:ss of actual datetime
select convert(  varchar, getdate() , 112) -- yyyymmdd
select convert( char(10), getdate() ,  20) -- yyyy-mm-dd limited by 10 characters

DATETIME cold be calculated in seconds and one interesting result mixing these four function is to show a formated difference um hours, minutes and seconds (hh:mm:ss) between two dates:

declare  @date1 datetime, @date2 datetime
set @date1=DATEADD(s,-638,getdate())
set @date2=GETDATE()

select convert(char(8),dateadd(s,datediff(s,@date1,@date2),'1900-1-1'),8)

... the result is 00:10:38 (638s = 600s + 38s = 10 minutes and 38 seconds)

Another example:

select distinct convert(char(8),dateadd(s,datediff(s, CRDATE , GETDATE() ),'1900-1-1'),8) from sysobjects order by 1

Answer 4

CREATE FUNCTION getDateDiffHours(@fdate AS datetime,@tdate as datetime) RETURNS varchar (50) AS BEGIN DECLARE @cnt int DECLARE @cntDate datetime DECLARE @dayDiff int DECLARE @dayDiffWk int DECLARE @hrsDiff decimal(18)

DECLARE @markerFDate datetime
DECLARE @markerTDate datetime

DECLARE @fTime int
DECLARE @tTime int 


DECLARE @nfTime varchar(8)
DECLARE @ntTime varchar(8)

DECLARE @nfdate datetime
DECLARE @ntdate datetime

-------------------------------------
--DECLARE @fdate datetime
--DECLARE @tdate datetime

--SET @fdate = '2005-04-18 00:00:00.000'
--SET @tdate = '2005-08-26 15:06:07.030'
-------------------------------------

DECLARE @tempdate datetime

--setting weekends
SET @fdate = dbo.getVDate(@fdate)
SET @tdate = dbo.getVDate(@tdate)
--RETURN @fdate 

SET @fTime = datepart(hh,@fdate)
SET @tTime = datepart(hh,@tdate)
--RETURN @fTime 
if datediff(hour,@fdate, @tdate) <= 9

        RETURN(convert(varchar(50),0) + ' Days ' + convert(varchar(50),datediff(hour,@fdate, @tdate)))  + ' Hours'
else
--setting working hours
SET @nfTime = dbo.getV00(convert(varchar(2),datepart(hh,@fdate))) + ':' +dbo.getV00(convert(varchar(2),datepart(mi,@fdate))) + ':'+  dbo.getV00(convert(varchar(2),datepart(ss,@fdate)))
SET @ntTime = dbo.getV00(convert(varchar(2),datepart(hh,@tdate))) + ':' +dbo.getV00(convert(varchar(2),datepart(mi,@tdate))) + ':'+  dbo.getV00(convert(varchar(2),datepart(ss,@tdate)))

IF @fTime > 17 
begin
    set @nfTime = '17:00:00'
end 
else
begin
    IF @fTime < 8 
        set @nfTime = '08:00:00'
end 

IF @tTime > 17 
begin
    set @ntTime = '17:00:00'
end 
else
begin
    IF @tTime < 8 
        set @ntTime = '08:00:00'
end 



-- used for working out whole days

SET @nfdate = dateadd(day,1,@fdate) 

SET @ntdate = @tdate
SET @nfdate = convert(varchar,datepart(yyyy,@nfdate)) + '-' + convert(varchar,datepart(mm,@nfdate)) + '-' + convert(varchar,datepart(dd,@nfdate))
SET @ntdate = convert(varchar,datepart(yyyy,@ntdate)) + '-' + convert(varchar,datepart(mm,@ntdate)) + '-' + convert(varchar,datepart(dd,@ntdate))
SET @cnt = 0
SET @dayDiff = 0 
SET @cntDate = @nfdate
SET @dayDiffWk = convert(decimal(18,2),@ntdate-@nfdate)

--select @nfdate,@ntdate

WHILE @cnt < @dayDiffWk
BEGIN   
    IF (NOT DATENAME(dw, @cntDate) = 'Saturday') AND (NOT DATENAME(dw, @cntDate) = 'Sunday')
    BEGIN 
        SET @dayDiff = @dayDiff + 1
    END 
    SET @cntDate = dateadd(day,1,@cntDate)
    SET @cnt = @cnt + 1
END 

--SET @dayDiff = convert(decimal(18,2),@ntdate-@nfdate) --datediff(day,@nfdate,@ntdate)
--SELECT @dayDiff

set @fdate = convert(varchar,datepart(yyyy,@fdate)) + '-' + convert(varchar,datepart(mm,@fdate)) + '-' + convert(varchar,datepart(dd,@fdate)) + ' ' + @nfTime
set @tdate = convert(varchar,datepart(yyyy,@tdate)) + '-' + convert(varchar,datepart(mm,@tdate)) + '-' + convert(varchar,datepart(dd,@tdate)) + ' ' + @ntTime

set @markerFDate = convert(varchar,datepart(yyyy,@fdate)) + '-' + convert(varchar,datepart(mm,@fdate)) + '-' + convert(varchar,datepart(dd,@fdate)) + ' ' + '17:00:00'
set @markerTDate = convert(varchar,datepart(yyyy,@tdate)) + '-' + convert(varchar,datepart(mm,@tdate)) + '-' + convert(varchar,datepart(dd,@tdate)) + ' ' + '08:00:00'

--select @fdate,@tdate
--select @markerFDate,@markerTDate

set @hrsDiff = convert(decimal(18,2),datediff(hh,@fdate,@markerFDate))

--select @hrsDiff
set @hrsDiff = @hrsDiff +  convert(int,datediff(hh,@markerTDate,@tdate))

--select @fdate,@tdate  

IF convert(varchar,datepart(yyyy,@fdate)) + '-' + convert(varchar,datepart(mm,@fdate)) + '-' + convert(varchar,datepart(dd,@fdate)) = convert(varchar,datepart(yyyy,@tdate)) + '-' + convert(varchar,datepart(mm,@tdate)) + '-' + convert(varchar,datepart(dd,@tdate))  
BEGIN
    --SET @hrsDiff = @hrsDiff - 9
    Set @hrsdiff = datediff(hour,@fdate,@tdate)
END 

--select FLOOR((@hrsDiff / 9))

IF (@hrsDiff / 9) > 0 
BEGIN
    SET @dayDiff = @dayDiff + FLOOR(@hrsDiff / 9)
    SET @hrsDiff = @hrsDiff - FLOOR(@hrsDiff / 9)*9
END 

--select convert(varchar(50),@dayDiff) + ' Days ' + convert(varchar(50),@hrsDiff)   + ' Hours'

RETURN(convert(varchar(50),@dayDiff) + ' Days ' + convert(varchar(50),@hrsDiff))    + ' Hours'

END

Answer 5

SELECT DATEDIFF (MyUnits, '2010-01-22 15:29:55.090', '2010-01-22 15:30:09.153')

Substitute "MyUnits" based on DATEDIFF on MSDN

Answer 6

Internally in SQL Server dates are stored as 2 integers. The first integer is the number of dates before or after the base date (1900/01/01). The second integer stores the number of clock ticks after midnight, each tick is 1/300 of a second.

More info here

Because of this, I often find the simplest way to compare dates is to simply substract them. This handles 90% of my use cases. E.g.,

select date1, date2, date2 - date1 as DifferenceInDays
from MyTable
...

When I need an answer in units other than days, I will use DateDiff.