The entity integrity rule states that
Correct answer: B. Each entity must have a primary key
- A. No primary key attribute can be null
- B. Each entity must have a primary key
- C. Referential integrity must be maintained across all entities
- D. A primary key must have only one attribute
Explanation
Each entity must have a primary key is the core principle of the entity integrity rule. A primary key is a unique identifier for each row (record) in a table. It ensures that every entity (represented by a row) can be distinctly identified and retrieved from the database In conclusion, the entity integrity rule fundamentally requires that each entity (row) in a database table must have a primary key for proper identification and data integrity.
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