Question at position 16 Which statement best describes an Entity–Relationship (ER) data structure?It is made up of tables linked using keys, with data joined together when needed by the systemIt stores all data in a single flat file with no relationships between recordsIt represents information purely as documents with no explicit structureIt uses nodes and edges to represent everything as a graph that can be walkedClear my selection

Question

BlackTom AI · Accepted Answer

An Entity–Relationship (ER) model represents entities (things of interest), their attributes (properties), and the relationships between them; in practical systems this is mapped to tables (relations) that are linked by keys so related data can be joined.

1) Relevant knowledge points and concepts
- ER diagram concepts: entity, attribute, relationship, cardinality.  
- Relational implementation: each entity typically becomes a table; attributes become columns.  
- Keys: primary keys uniquely identify table rows; foreign keys reference primary keys in other tables to express relationships.  
- Joins: SQL uses join operations to combine related rows from different tables when needed.  
- Alternatives: flat files (no relations), document stores (documents with nested structure), and graph databases (nodes and edges) are different data models.

2) Step-by-step reasoning
- ER models explicitly capture relationships; relational databases implement this by creating tables for entities and using keys to link them.  
- When data from multiple entities is required, the DBMS performs join operations using the defined keys to assemble the combined result.  
- Therefore the ER approach matches the description of “tables linked using keys, with data joined together when needed.”

3) Calculations
- Not applicable; the reasoning is conceptual rather than numeric.

4) Why the correct answer is correct
- The correct option describes exactly how ER designs are implemented in relational databases: tables, primary/foreign keys, and join operations correspond directly to entities, relationships, and attributes from the ER model.

5) Why the other options are incorrect
- “Single flat file with no relationships”: contradicts ER’s focus on explicit relationships.  
- “Represents information purely as documents”: describes document-oriented NoSQL stores, not ER models.  
- “Uses nodes and edges to represent everything as a graph”: describes graph databases, a different model from ER/relational.

6) Conclusion
The correct answer is: “It is made up of tables linked using keys, with data joined together when needed by the system,” which matches the provided answer.

类似问题

Which of the following best illustrates the relationship between entities and attributes?

Question at position 46 The number of entity types that participate in a relationship is called the: degree.identifying characteristic.number.counter.

Question at position 23 The most common types of entities are:strong entities.associative entities.super entities.weak entities.

Which statement about participation constraints is MOST accurate?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单