protected function _createPlaceholders($fields)
        {
            if (!empty($fields)) {
                $db_fields = [];

                foreach($fields as $key => $value) {
                    // Process expression fields directly into the query
                    if(Arrays::exists($key, $this->_expr_fields)) {
                        $db_fields[] = $value;
                    } else {
                        $db_fields[] = '?';
                    }
                }

                return implode(', ', $db_fields);
            }
        }