Not sure, but I think that you must extract it in its character format;
something like:
convert (nvarchar (10), MyDateTimeField, 102)
Of course, you can also add a level of conversion to get it back in DateTime
format:
convert (DateTime, convert (DateTime, MyDateTimeField, 102), 102)
Or:
convert (DateTime, convert (DateTime, MyDateTimeField, 102) + '
12:00:00 AM', 102)
There is also the function DatePart (....).