public function delete_many($primary_values)
    {
        $primary_values = $this->trigger('before_delete', $primary_values);

        $this->_database->where_in($this->primary_key, $primary_values);

        if ($this->soft_delete)
        {
            $result = $this->_database->update($this->_table, array( $this->soft_delete_key => TRUE ));
        }
        else
        {
            $result = $this->_database->delete($this->_table);
        }

        $this->trigger('after_delete', $result);

        return $result;
    }