use COALESCE to ensure integer values

db/zm_update-1.31.33.sql

@@ -0,0 +1,31 @@
+drop trigger if exists event_delete_trigger;
+
+delimiter //
+
+CREATE TRIGGER event_delete_trigger BEFORE DELETe on Events
+
+FOR EACH ROW
+  BEGIN
+    call update_storage_stats(OLD.StorageId, -OLD.DiskSpace);
+    DELETE FROM Events_Hour WHERE EventId=OLD.Id;
+    DELETE FROM Events_Day WHERE EventId=OLD.Id;
+    DELETE FROM Events_Week WHERE EventId=OLD.Id;
+    DELETE FROM Events_Month WHERE EventId=OLD.Id;
+    IF ( OLD.Archived ) THEN
+      DELETE FROM Events_Archived WHERE EventId=OLD.Id;
+      UPDATE Monitors SET
+      ArchivedEvents = ArchivedEvents - 1,
+      ArchivedEventDiskSpace = COALESCE(ArchivedEventDiskSpace,0) - COALESCE(OLD.DiskSpace,0),
+      TotalEvents = TotalEvents - 1,
+      TotalEventDiskSpace = COALESCE(TotalEventDiskSpace,0) - COALESCE(OLD.DiskSpace,0)
+      WHERE Id=OLD.MonitorId;
+    ELSE
+      UPDATE Monitors SET
+      TotalEvents = TotalEvents-1,
+      TotalEventDiskSpace=COALESCE(TotalEventDiskSpace,0)-COALESCE(OLD.DiskSpace,0)
+      WHERE Id=OLD.MonitorId;
+  END IF;
+END;
+
+//
+