Unnecessary data duplication in a relational database that arises when a table stores a column that can be calculated or derived from other columns already present. For example, storing a 'current age' column in a table that already has a date-of-birth column is redundant, since age can always be computed. Redundant columns risk data inconsistency and update anomalies, and are generally eliminated through normalization.

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• 2020r02o #57次に示す項目を使って関係データベースで管理する“社員”表を設計する。他の項目から導出できる，冗長な項目はどれか。 社員 | 社員番号 | 社員名 | 生年月日…