public function delete($id)
{
$this->db->trans_start();
# delete company related by field
$this->load->model("JobModel");
$job = new JobModel();
$job->delete_by_field($id);
# remove the field itself
$condition = array(JobFieldModel::$primary_key => $id);
$this->db->delete(JobFieldModel::$table_name, $condition);
$this->db->trans_complete();
return $this->db->trans_status();
}