--- a/displayCalendar.php
+++ b/displayCalendar.php
@@ -8,7 +8,7 @@
 $monthParts = explode("-",$_REQUEST['month']);
   $query = 'SELECT "CNID", "description", "value", "agencyName", "category", "contractStart", "supplierName"
     FROM contractnotice
-    WHERE "childCN" = 0 
+    WHERE "childCN" is null
     AND extract(year from "contractStart") = :year
     AND extract(month from "contractStart")  = :month
     ORDER BY value DESC';
@@ -61,7 +61,7 @@
 
 
 $query = 'SELECT extract(year from "contractStart"), extract(month from "contractStart"),
-SUM(value) as val, count(1) as count FROM contractnotice WHERE "childCN" = 0 GROUP BY extract(year from "contractStart"), extract(month from "contractStart") ORDER BY extract(year from "contractStart"), extract(month from "contractStart") ';
+SUM(value) as val, count(1) as count FROM contractnotice WHERE "childCN" is null GROUP BY extract(year from "contractStart"), extract(month from "contractStart") ORDER BY extract(year from "contractStart"), extract(month from "contractStart") ';
 $query = $conn->prepare($query);
   $query->execute();
   if (!$query) {