What is a primary key in the context of an ER model?
Practice Questions
1 question
Q1
What is a primary key in the context of an ER model?
A key that allows for data redundancy
A unique identifier for each entity instance
A foreign key that links to another table
A type of relationship between entities
A primary key is a unique identifier for each instance of an entity, ensuring that no two instances are the same.
Questions & Step-by-step Solutions
1 item
Q
Q: What is a primary key in the context of an ER model?
Solution: A primary key is a unique identifier for each instance of an entity, ensuring that no two instances are the same.
Steps: 5
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.
