Age Duration Calculation

ALTER FUNCTION [dbo].[GetDurationYear_Month_Day]         
(         
   @FromDate DATETIME, @ToDate DATETIME         
)         
RETURNS NVARCHAR(300)         
AS         
BEGIN 

DECLARE @date datetime, @tmpdate datetime, @years int, @months int, @days int
Declare @currentdatetime datetime 

--SELECT @date = '15-Jun-1986'


set @date = @FromDate
 
set @currentdatetime = @ToDate


 --SELECT
 -- @date = REPLACE(CONVERT(Date,e.DateOfBirth,103),' ','-'),
 
 -- @currentdatetime =  REPLACE(CONVERT(Date,e.FirstJoiningDate,103),' ','-')                                 

 --  FROM Employee as e WHERE e.EmployeeId = 26380 --12390
 
   
SELECT @tmpdate = @date

SELECT @years = DATEDIFF(yy, @tmpdate, @currentdatetime) - CASE WHEN (MONTH(@date) > MONTH(@currentdatetime)) OR (MONTH(@date) = MONTH(@currentdatetime) AND DAY(@date) > DAY(@currentdatetime)) THEN 1 ELSE 0 END
SELECT @tmpdate = DATEADD(yy, @years, @tmpdate)
SELECT @months = DATEDIFF(m, @tmpdate, @currentdatetime) - CASE WHEN DAY(@date) > DAY(@currentdatetime) THEN 1 ELSE 0 END
SELECT @tmpdate = DATEADD(m, @months, @tmpdate)
SELECT @days = DATEDIFF(d, @tmpdate, @currentdatetime)



 RETURN CAST(@years AS VARCHAR(4)) + '-' + CAST(@months AS VARCHAR(4)) + '-' + CAST(@days AS VARCHAR(4))


END