問62
頻出度★★★
関係データベースのデータを正規化することによって得られる効果として,適切なものはどれか。
平成29年度 秋期 ITパスポート試験 問62
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 62
Incorrectア
Data compatibility between different types of computers is ensured by standardizing and converting character codes and data formats (for example, common formats such as CSV or XML). Normalization is a design technique for organizing the table structure within a single database, and has nothing to do with compatibility between computer models.
Incorrectイ
Improving storage efficiency belongs to compression technology and storage management. Because normalization reduces duplication, it does save capacity as a side effect, but that is not an effect of compression processing. This deviates from the main purpose of normalization asked here (eliminating redundancy and inconsistency), so it is inappropriate.
- ウ
正解 Normalization is a design technique that divides and organizes the tables of a relational database into appropriate units without duplication or waste. When the same data is stored redundantly in multiple places, updating only part of it causes an inconsistency (contradiction). Normalization eliminates this duplication and keeps each piece of data in only one place, thereby preventing inconsistencies during updates. Therefore the effect obtained is eliminating data redundancy and inconsistency, which is choice ウ.
Incorrectエ
Backup is an operational measure that prepares for device failure or data loss, and its purpose is completely different from that of normalization. Even after normalization, the risk of device failure remains, so there is no cause-and-effect relationship by which backups could be omitted.
ここがポイント
- The purpose of normalization is to eliminate data redundancy and prevent inconsistencies (contradictions) during updates. It is a design technique that divides and organizes tables into appropriate units.
- Storage efficiency, compatibility between computer models, and backup are technical or operational issues separate from normalization, and are not direct effects of normalization.
用語