How can I rewrite a date field "End Date" to be "present" if no value is entered?
When there is no end date specified for a node it takes both the dates same. The module consider it a one day event.

However, in your case you are making it ongoing by not mentioning the end_date so no results behavior is not going to work. I would suggest to use some global php like this

&lt;?php
if($row-&gt;field_date == $row-&gt;field_date_1) {
   echo "Present";
} else {
  echo $row-&gt;field_date_1;
}
?&gt;


Make sure to include this php field after both start and end date fields, and make the end date fields hidden.