An entity that cannot exist without a strong entity
An entity with no attributes
An entity that has a composite key
An entity that is not related to any other entity
Correct Answer: An entity that cannot exist without a strong entity
Solution:
A weak entity is one that cannot exist without a strong entity.
What is a weak entity in an ER model?
Practice Questions
Q1
What is a weak entity in an ER model?
An entity that cannot exist without a strong entity
An entity with no attributes
An entity that has a composite key
An entity that is not related to any other entity
Questions & Step-by-Step Solutions
What is a weak entity in an ER model?
Correct Answer: A weak entity is one that cannot exist without a strong entity.
Step 1: Understand that an entity is something that can be identified, like a person or a car.
Step 2: Know that a strong entity can exist on its own, meaning it has its own unique identifier (like an ID number).
Step 3: Learn that a weak entity is different because it cannot exist by itself; it needs a strong entity to help identify it.
Step 4: Realize that a weak entity usually has a partial key, which means it needs the strong entity's key to be fully identified.
Step 5: For example, think of a 'Room' as a weak entity that needs a 'Building' (strong entity) to be identified, like 'Room 101 in Building A'.
Weak Entity – A weak entity is an entity that does not have a primary key and relies on a strong entity for its identification.
Strong Entity – A strong entity is an entity that has a primary key and can exist independently.
Identifying Relationship – The relationship between a weak entity and its corresponding strong entity, which is used to uniquely identify the weak entity.
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