Topic 04, Part 10 - Types of Weak Entities

Dr. Soper discusses the different types of weak entities that can be used when creating entity-relationship models. This video is Part 10 of Topic 04 in Dr. Soper's class on Database Design and Management.

[syedburhanofficial]

Great job on your efforts! However, I believe there may be a slight confusion between Weak Relationship and Weak Entity. At 11:39, the ID Dependent and Non ID Dependent are actually Strong and Weak Relationships, respectively. Non ID Dependent does not refer to a weak entity, but rather to a Strong Entity with a Weak Relationship.

In order for an entity to be classified as a weak entity, it must meet two conditions:
1. The entity is existence-dependent on a parent entity.
2. The entity has a primary key that is partially or totally derived from the parent entity in the relationship.

In figure (b) at 11:39, the entity is existence-dependent on the parent entity, satisfying the first condition. However, it does not satisfy the second condition as a surrogate key "VIN" is used to identify the entity, rather than a primary key derived from the parent entity. Therefore, figure (b) cannot be classified as a weak entity. On the other hand, figure (a) does satisfy both conditions and can be classified as a weak entity.

Please let me know if my understanding is correct, and kindly correct me if I have misunderstood anything.