USE pubs
GO
SELECT 
	DATEDIFF(DAY, pubdate, GETDATE()) AS Anzahl_Tage
FROM 
	titles
GO 

Anzahl_Tage 
----------- 
4761
4764
4743
4751
4764
4755
1418
4743
3665
1418
4630
4758
4646
4761
4761
4630
4761
4761

(18 row(s) affected)