問76
頻出度★★★
データベースの内容を，利用者の業務の機密性に応じて限定的に表示するようにしたい。その手法として，最も適切なものはどれか。
平成21年度 秋期 ITパスポート試験 問76
This question's explanation and your answers so far.
解説
問 76
- ア
正解 ア is correct. With access control in a DBMS, access rights (read, insert, update, delete, and so on) can be set for each combination of “data” (tables, columns, rows, views) and “user” (or role). This makes it possible to keep sharing one and the same database while showing highly confidential items only to authorized users and hiding them from others, which is exactly restricted display. Because the actual data stays under single, centralized management, consistency and up-to-dateness are preserved while what is shown can still be controlled according to the confidentiality of the work, so this is the most appropriate method.
Incorrectイ
If a copy is distributed to each user, many copies come to exist, updates that fail to be reflected cause inconsistency, and losing or carrying out a copy itself adds a new risk of information leakage. This cannot be called a method of restricting what is displayed while sharing a database, and it is the least appropriate direction.
Incorrectウ
A design that provides a dedicated column for each user requires changing the structure of the table (its columns) every time a user is added, and data with the same meaning is duplicated and becomes redundant. Moreover, merely adding a column does not make that column invisible to other users, so it does not serve as a means of controlling confidentiality.
Incorrectエ
Setting a password for each record (row) makes managing, distributing, and changing passwords practically unworkable as the number of records grows. It cannot grant rights according to the content of each user's work, and anyone who knows the password can read the data, so it is not appropriate as a method of restricted display based on confidentiality.
ここがポイント
- Access rights (access control) = a mechanism that defines, by combination, “who” may perform “which operations” on “which data”. It is the basic means of ensuring the confidentiality of a database.
- The principle is to keep the data under single, centralized management and control what is shown by means of rights. Distributing copies, or physically creating separate columns or rows per user, only brings redundancy, inconsistency, and management burden, and is not a solution.
用語