Get Difference Between two Dates in SQL Server

To get the difference between two dates use the following query
 
For Days difference
  1. Select datediff(DAY,'2013-12-11 23:37:29.983',GETDATE()) 
For Month's difference
  1. Select datediff(MONTH,'2013-12-11 23:37:29.983',GETDATE()) 
For year difference
  1. Select datediff(YEAR,'2013-12-11 23:37:29.983',GETDATE())