Difference between two dates in SQL Server

If you want to get the difference between two dates in SQL Server then you need to make use of DATEDIFF function. 

DECLARE @StartDate DATETIME
SET @StartDate = '2012-03-08 12:22:00.000'

Declare @EndDate DATETIME
SET @EndDate =  '2012-03-12 11:32:00.000' 

--To get only Hours
SELECT DATEDIFF(hh, @StartDate,@EndDate ) AS [Hours];

--To get the result in Minutes
SELECT CAST(DATEDIFF(ss, @StartDate, @EndDate) AS DECIMAL(10, 0)) / 60 AS [Minutes];

--To get both Hours and Minutes
SELECT DATEDIFF(hh, @StartDate, @EndDate) AS [Hours],
DATEDIFF(mi,DATEADD(hh,DATEDIFF(hh, @StartDate, @EndDate),@StartDate),@EndDate) AS [Minutes];