Data Modeling 面接の質問と回答
質問 1. What is data modeling?
Data modeling is the process of creating a visual representation of the structure and relationships within a database. It helps in understanding and organizing data for efficient storage, retrieval, and management.
Example:
Example: Entity-Relationship Diagram (ERD) or UML Class Diagram.
質問 2. Explain the difference between logical and physical data models.
Logical data models focus on representing data at a high level, emphasizing business concepts and relationships. Physical data models, on the other hand, detail how data is stored in the database, including tables, columns, indexes, etc.
Example:
Example: Logical model may have entities like 'Customer' and 'Order,' while the physical model includes details like 'Customer' table with 'customer_id' and 'Order' table with 'order_date.'
質問 3. What is normalization and denormalization in database design?
Normalization is the process of organizing data to reduce redundancy and improve data integrity. Denormalization, on the other hand, involves introducing redundancy to improve query performance.
Example:
Example: Normalizing a 'Product' table by separating it into 'Product' and 'Supplier' tables to eliminate duplicate supplier information.
質問 4. Explain the concept of cardinality in data modeling.
Cardinality defines the relationship between two entities, indicating how many instances of one entity are related to a specific instance of another entity. It is expressed as 'one-to-one,' 'one-to-many,' or 'many-to-many.'
Example:
Example: In a 'Customer' and 'Order' relationship, cardinality may be 'one-to-many,' indicating a customer can place multiple orders.
質問 5. What is a surrogate key?
A surrogate key is an artificial key assigned to uniquely identify each record in a table. It is typically a system-generated or sequentially assigned value and is used as the primary key.
Example:
Example: Using an auto-incremented integer as a surrogate key for a 'Product' table.
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