function __construct($report_id, $plugin_id, $creator_id, $reportfield_id = null)
 {
     parent::__construct($report_id, $plugin_id, $creator_id, $reportfield_id);
     $this->tablename = "block_ilp_plu_gradebooktracker";
     //$this->data_entry_tablename = "block_ilp_plu_gradebooktracker_ent";
 }
 function __construct($report_id, $plugin_id, $creator_id, $reportfield_id = null)
 {
     parent::__construct($report_id, $plugin_id, $creator_id, $reportfield_id = null);
     //remember to define $this->tablename and $this->items_tablename in the child class
 }