title: How can I have an empty date in a DateTime object?
body: <p>When I get dates from a MySQL query, some of them are NULL, because unknown.
  However, when I translate them into PHP using date_create, null dates are replaced by the today date by default, ehich is not what I want.
  I tried to set the date properety Inside the date object to null or an empty string to no avail.
  Is there some way I can get rid of this default date?</p>