問69
頻出度★★★
関係データベースにおけるデータの正規化に関する次の記述中の a，b に入れる字句の適切な組合せはどれか。 正規化の主な目的として，データの重複を排除し，a ことが挙げられる。 正規化には複数の段階があり，これを進めていくと，b 。
令和8年度 ITパスポート試験 問69
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 69
Incorrectア
b (one table is split into multiple tables) is correct, but a “improve the compression ratio” is wrong. Normalization is not an operation aimed at compressing data volume; its goal is to ensure data consistency.
Incorrectイ
Both a “improve the compression ratio” and b “multiple tables are merged into one table” are wrong. Normalization is not for compression, and it proceeds in the direction of splitting tables rather than merging them.
- ウ
正解 Normalization mainly aims to remove data duplication (redundancy) and to maintain consistency so that values do not become contradictory when updated. Therefore a should be “maintain consistency”. Also, as normalization proceeds from the 1st to the 2nd to the 3rd normal form, it focuses on the dependency relationships among items and decomposes one large table into multiple tables. Therefore b should be “one table is split into multiple tables”. The combination that satisfies both is ウ.
Incorrectエ
a (maintain consistency) is correct, but b “multiple tables are merged into one table” is wrong. Normalization does not merge tables; instead, it splits tables to remove redundancy.
ここがポイント
- The purpose of normalization: to eliminate data duplication (redundancy) and prevent contradictions when updating, thereby maintaining data consistency. Data compression is not its purpose.
- The process of normalization: as the stages proceed from the 1st to the 2nd to the 3rd normal form, one table is split into multiple tables based on functional dependency (not merged).
用語