What is a primary key in the context of an ER model?

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Question: What is a primary key in the context of an ER model?

Options:

Correct Answer: A unique identifier for each entity instance

Solution:

A primary key is a unique identifier for each instance of an entity, ensuring that no two instances are the same.

What is a primary key in the context of an ER model?

What is a primary key in the context of an ER model?

Correct Answer: A primary key is a unique identifier for each instance of an entity.

Step 1: Understand what an entity is. An entity is something that can be identified, like a person, place, or thing.
Step 2: Realize that each entity can have many instances. For example, the entity 'Student' can have many students like Alice, Bob, and Charlie.
Step 3: Know that a primary key is a special attribute (or a combination of attributes) that uniquely identifies each instance of an entity.
Step 4: Understand that the primary key must be unique, meaning no two instances can have the same primary key value. For example, each student might have a unique student ID.
Step 5: Remember that the primary key helps to avoid confusion and ensures that each instance can be easily found and referenced.

Primary Key – A primary key is a unique identifier for each instance of an entity in an ER model, ensuring data integrity and uniqueness.