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

Just a caveat to add about DateDiff, it counts the number of times you pass the boundary you specify as your units, so is subject to problems if you are looking for a precise timespan. e.g.

select datediff (m, '20100131', '20100201')

gives an answer of 1, because it crossed the boundary from January to February, so even though the span is 2 days, datediff would return a value of 1 - it crossed 1 date boundary.

select datediff(mi, '2010-01-22 15:29:55.090' , '2010-01-22 15:30:09.153')

Gives a value of 1, again, it passed the minute boundary once, so even though it is approx 14 seconds, it would be returned as a single minute when using Minutes as the units.