<?php
  $ship_date = $row['ship_date'];;
  $ship_date = date("m-d-Y", strtotime($ship_date));
?>

$ship_date = $row['ship_date'];
if ($ship_date == NULL){
  $ship_date = "";
}
else {
  $ship_date = date("m-d-Y", strtotime($ship_date));
}