ALTER FUNCTION [dbo].[get_FullAge] (  @birthday datetime, @currentDay datetime ) RETURNS INT AS BEGIN DECLARE @age INT SET @age = DATEDIFF(YEAR, @birthday, @currentDay) IF DATEDIFF(DAY, DATEADD(YEAR, @age, @birthday), @currentDay) <= 0  SET @age = @age - 1 IF DATEPART(MONTH, @birthday) = 2 AND DATEPART(DAY, @birthday) = 29 AND DATEPART(MONTH, @currentDay) = 3  AND DATEPART(DAY, @currentDay) = 1 AND  NOT (YEAR(@currentDay) % 4 = 0 AND (YEAR(@currentDay) % 100 !=0 OR YEAR(@currentDay) % 400 = 0))  SET @age = @age - 1 IF @age < 0  SET @age = 0   RETURN @age END