Datediff Function Sql Server

DateDiff function returns the  difference between to dates

Suppose we have employee table and it has following rows and columns

Id	Name	Description	JoiningDate
1	Test1	Executive	10/5/2013 0:00
2	Test2	S.Executive	10/5/2012 0:00
3	Test3	Team Lead	10/5/2012 0:00
4	Test4	Jr Engineer	10/11/2014 0:00

Calculate the Employee joining Year, month and days

  select name, datediff(year,JoiningDate,getdate()) Year  , datediff(year,JoiningDate,getdate()) month ,datediff(DAY,JoiningDate,getdate()) day from Employee  where joiningdate is not null

Calculate the age   Sql server in years-month and days

  Declare @dateofbirth datetime

  Declare @years int

  declare @months int

  declare @days int

  declare @temp date

  set @dateofbirth='1983-04-27';

  set @temp  =@dateofbirth

  set @years = (select DATEDIFF(yy, @temp, GETDATE())- CASE WHEN (MONTH(@dateofbirth) > MONTH(GETDATE())) OR (MONTH(@dateofbirth) = MONTH(GETDATE()) AND DAY(@dateofbirth) > DAY(GETDATE())) THEN 1 ELSE 0 END)

SET @temp = DATEADD(yy, @years, @temp)

SET @months = DATEDIFF(m, @temp, GETDATE()) - CASE WHEN DAY(@dateofbirth) > DAY(GETDATE()) THEN 1 ELSE 0 END

SET @temp = DATEADD(m, @months, @temp)

SET @days = DATEDIFF(d, @temp, GETDATE())

select @years as TotalYear ,@months as M