The simple one line solution is
datediff(dd,'2010-12-31 15:13:48.593','2010-12-31 00:00:00.000')=0
datediff(dd,'2010-12-31 15:13:48.593','2010-12-31 00:00:00.000')<=1
datediff(dd,'2010-12-31 15:13:48.593','2010-12-31 00:00:00.000')>=1
You can try various option with this other than "dd"