Oh, be careful now. I know this is an old post but the code above doesn't work 100% of the time. For example, it returns "0" years if @DOB = '2000-03-31' and the current date is '2001-03-31'. The problem is that DY contains different values for dates after 28 Feb for ALL leap years.

Try it yourself...

DECLARE @DOB datetime

,@Now datetime

SELECT @DOB = '3/31/2000'

,@Now = '3/31/2001'

SELECT CASE

WHEN DATEPART(DY,@Now) >= DATEPART(DY,@DOB)

THEN DATEDIFF(YY,@DOB,@Now)

ELSE DATEDIFF(YY,@DOB,@Now)-1

END

;