public function getFields()
    {
        $joins = $this->_sql->getJoins();
        $fields = $this->_sql->getFields();

        if (!is_array($fields)) {
            return $fields;
        }

        if (count($joins) > 0 && $this->_sql->prefixTableName) {
            $table = $this->_sql->getTableName();
            foreach ($fields as $key => $field) {
                $fields[$key] = "{$table}.{$field}";
            }
        }

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