問1
頻出度★★★
E-R図を使用してデータモデリングを行う理由として, 適切なものはどれか。
令和3年度 ITパスポート試験 問1
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 1
Incorrectア
Grasping how data is exchanged in business operations and clarifying the workflow is the role of a business flow diagram (workflow diagram), which represents the flow and procedures of the business. An E-R diagram represents not the flow of processing but the relationships among managed objects, so its purpose is different and this option is wrong.
Incorrectイ
Grasping the flow of data in current business operations and clarifying its problems is the aim of a DFD (data flow diagram), which represents the flow of data together with processes and data stores. An E-R diagram represents not the flow of data but the relationships among managed objects, so its purpose is likewise different and this option is wrong.
- ウ
正解 An E-R diagram (Entity-Relationship diagram) is a method for representing, in diagram form, the entities that a business deals with — that is, managed objects such as customers and products — together with the relationships among them. The purpose of using an E-R diagram in data modeling is precisely to make clear how the managed objects are connected to one another and what those relationships mean for the business. Therefore, option ウ, which diagrams the relationships among the business's managed objects such as customers and products and clarifies their business meaning, is correct.
Incorrectエ
Examining data items in detail and clarifying the implementation method of the database is a matter of physical design (design at the implementation level). Data modeling with an E-R diagram is not about deciding the implementation method but is the stage of conceptually organizing the managed objects and their relationships, so this option is wrong.
ここがポイント
- An E-R diagram is a data modeling technique that diagrams entities (managed objects) and relationships to clarify the data structure and its business meaning.
- Distinguish it from a business flow diagram, which represents business processing procedures, a DFD, which represents the flow of data, and physical design, which decides the implementation — their purposes differ.
用語