Calculating Age from date of birth

DECLARE	@Sample TABLE
	(
		Birthday DATE NOT NULL
	);

INSERT	@Sample
	(
		Birthday
	)
VALUES	('19940704'),
	('19950911'),
	('19941010'),
	('20120731'),
	('20120801'),
	('19990221');

-- code
SELECT	BirthDay,
	DATEDIFF(YEAR, Birthday, GETDATE()) - (100 * MONTH(Birthday) + DAY(Birthday) - 1) / 801 AS Age
FROM	@Sample;