What is a common characteristic of a weak entity in database design?

A common characteristic of a weak entity is that it relies on a relationship with another entity for identification. Weak entities are dependent on a strong entity (often referred to as an owner entity) for their identification and existence. This dependency means that a weak entity does not have a primary key that is unique by itself. Instead, it is identified through a combination of its own attributes and the primary key of the associated strong entity.

In a database model, a weak entity typically has a partial key, which is insufficient to uniquely identify an instance without the strong entity. This relationship is crucial because it enables the weak entity to derive its identity through the connection with the stronger entity, reflecting a fundamental aspect of the entity-relationship model in database design.

This characteristic contrasts with entities that have their own unique identifiers and can exist independently, which is not the case for weak entities. Additionally, while weak entities can have attributes, those attributes do not provide a means of unique identification without referencing the strong entity.