The identifier of the entity type becomes which of the following of the relations?
Correct answer: D. Primary key
- A. Foreign key
- B. Composite key
- C. Secondary key
- D. Primary key
Explanation
In the Entity-Relationship (ER) model, an entity type represents a class of real-world objects (e.g., customer, product, order). Each entity type has a unique identifier that distinguishes each instance of the entity type from all others. This identifier is mapped to a primary key in the corresponding relation (table) in a relational database.Primary Key: A primary key is a set of attributes (columns) in a relation that uniquely identifies each tuple (row) in the relation. There can only be one primary key per relation.
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