This method includes a form of "every 4 years" leap year support. It assumes a lifetime will rarely exceed 99 years and so foregoes making allowances for the 100 year (and beyond) leap year aberrations. In addition, this method can be easily used directly in a select statement. Of course the floating point math will not yield maximum performance. Opinions on this are greatfully solicited.

DECLARE @Years INT

DECLARE @DOB DATETIME

DECLARE @Compare DATETIME

SELECT @Years = ROUND((CONVERT(FLOAT,DATEDIFF(DAY,@DOB,@Compare)) - CONVERT(FLOAT,DATEDIFF(YEAR,@DOB,@Compare)) / CONVERT(FLOAT,4)) / CONVERT(FLOAT,365),0,3)