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      Question

      What is an 'ER Diagram' (Entity-Relationship Diagram)

      used for in database design?
      A To show the execution plan of SQL queries Correct Answer Incorrect Answer
      B To visually model the data entities, their attributes, and the relationships between them during database design Correct Answer Incorrect Answer
      C To map the physical storage locations of database files Correct Answer Incorrect Answer
      D To illustrate the network topology of the database server infrastructure so that relationships can be identified among the network components Correct Answer Incorrect Answer
      E To document the access permissions of different database users Correct Answer Incorrect Answer

      Solution

      An ER diagram is a conceptual data model showing: Entities (tables e.g., Customer, Account, Branch), Attributes (columns e.g., CustomerID, Name), and Relationships (e.g., Customer HAS Account — cardinality: one-to-many). Cardinalities: 1:1, 1:N, M:N. ER diagrams are created during the database design phase before actual table creation, serving as a blueprint for the relational schema. They are converted to physical schema during implementation.

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