function customDataFrom()
{
parent::customDataFrom();
$params = array('name' => 'HRJobContract_Summary');
CRM_Core_DAO::commonRetrieve('CRM_Core_DAO_CustomGroup', $params, $cGrp);
if (!$this->isFieldSelected($this->_columns[$cGrp['table_name']])) {
$mapper = CRM_Core_BAO_CustomQuery::$extendsMap;
$extendsTable = $mapper[$cGrp['extends']];
$baseJoin = CRM_Utils_Array::value($cGrp['extends'], $this->_customGroupExtendsJoin, "{$this->_aliases[$extendsTable]}.id");
$this->_from .= " LEFT JOIN {$cGrp['table_name']} {$this->_aliases[$cGrp['table_name']]} ON {$this->_aliases[$cGrp['table_name']]}.entity_id = {$baseJoin}";
}
}