How to calculate difference in hours (decimal) between two dates in SQL Server?

Question

I have to calculate the difference in hours (decimal type) between two dates in SQL Server 2008.

I couldn\'t find any useful technique to convert datetime to decimal

Answer 1

DATEDIFF but note it returns an integer so if you need fractions of hours use something like this:-

CAST(DATEDIFF(ss, startDate, endDate) AS decimal(precision, scale)) / 3600

Answer 2

Declare @date1 datetime
Declare @date2 datetime

Set @date1 = '11/20/2009 11:00:00 AM'
Set @date2 = '11/20/2009 12:00:00 PM'

Select Cast(DateDiff(hh, @date1, @date2) as decimal(3,2)) as HoursApart

Result = 1.00

Answer 3

DATEDIFF(hour, start_date, end_date) will give you the number of hour boundaries crossed between start_date and end_date.

If you need the number of fractional hours, you can use DATEDIFF at a higher resolution and divide the result:

DATEDIFF(second, start_date, end_date) / 3600.0

The documentation for DATEDIFF is available on MSDN:

http://msdn.microsoft.com/en-us/library/ms189794%28SQL.105%29.aspx

Answer 4

You are probably looking for the DATEDIFF function.

DATEDIFF ( datepart , startdate , enddate )

Where you code might look like this:

DATEDIFF ( hh , startdate , enddate )

Answer 5

Using Postgres I had issues with DATEDIFF, but had success with this:

  DATE_PART('day',(delivery_time)::timestamp - (placed_time)::timestamp) * 24 + 
  DATE_PART('hour',(delivery_time)::timestamp - (placed_time)::timestamp) +
  DATE_PART('minute',(delivery_time)::timestamp - (placed_time)::timestamp) / 60

which gave me an output like "14.3"

Answer 6

DATEDIFF(minute,startdate,enddate)/60.0)

Or use this for 2 decimal places:

CAST(DATEDIFF(minute,startdate,enddate)/60.0 as decimal(18,2))