問88
頻出度★★★
関係データベースにおいて, 正規化を行う目的はどれか。
平成28年度 秋期 ITパスポート試験 問88
テクノロジ系データベース › データベース設計
This question's explanation and your answers so far.
解説
問 88
Incorrectア
Linking related data with pointers to improve access efficiency belongs to network-model databases or to physical index and pointer design; it is not the purpose of normalization. On the contrary, because normalization splits tables, join processing increases and access efficiency can even decline.
Incorrectイ
Adding error-correcting codes to improve reliability is an error detection and correction technology used in communications or storage devices, and has nothing to do with normalization, which is the logical design of a database.
Incorrectウ
Encrypting data to ensure security is an information-security measure, a different technology from normalization, whose purpose is to eliminate data duplication.
- エ
正解 The correct answer is “エ”. Normalization is a design technique that splits the tables of a relational database according to certain rules so as to avoid storing the same data redundantly in multiple places. If data is managed centrally in only one location, then when a value is updated there is no need to fix every related location, so contradictions caused by missed updates (update inconsistency) become far less likely. As a result, data consistency is maintained and maintainability improves. Choice “エ” says exactly “Improve maintainability by not holding duplicate data, among other things,” which is precisely the purpose of normalization itself.
ここがポイント
- Normalization = a design technique that systematically splits tables to eliminate data duplication (redundancy), prevents update inconsistency, and thereby improves consistency and maintainability.
- Distinguish these: improving access efficiency (pointers, indexes), improving reliability (error-correcting codes), and ensuring confidentiality (encryption) are all separate technologies whose purposes differ from that of normalization.
用語