--- a/displayCategory.php
+++ b/displayCategory.php
@@ -5,7 +5,7 @@
     echo "<center><h1>".$_REQUEST['category']."</h1></center>";
   $query = "SELECT CNID, description, value, agencyName, category, contractStart, supplierName
     FROM `contractnotice`
-    WHERE childCN = 0 
+    WHERE childCN is null 
     AND category = '" . $_REQUEST['category'] . "'
     ORDER BY value DESC";
   $result = mysql_query($query);
@@ -39,7 +39,7 @@
     include_header("Categories");
 $query = "SELECT sum(value), category
 FROM `contractnotice`
-WHERE childCN = 0 
+WHERE childCN is null
 GROUP BY category ORDER BY sum(value) DESC ";
 $result = mysql_query($query);
   echo "<table>  <thead>