When is the concept of a weak entity used in data modeling? Define the terms owner entity type, weak entity type, identifying relationship type

DofotheroU

DofotheroU

Answered question

2021-09-15

When does data modeling use the idea of a weak entity? Give definitions for the terms partial key, weak entity type, identifying relationship type, and owner entity type.

Answer & Explanation

Latisha Oneil

Latisha Oneil

Skilled2021-09-16Added 100 answers

When specifying a new entity type that is similar to one we already have, the concept of weak entity types is used in data modeling, but we want this new entity type to have specific attributes and to be able to participate in specific relationships.
If the newly created entity type lacks important attributes, it is called weak entity type and it needs to be related to a strong entity type (directly or indirectly) that has: key attributes of its own.
Owner (or identifying) entity type is a title for entity type that identifies weak entity types related to it. Weak entity types include one of their attributes when combining with owner entity type.
A weak entity type is one that lacks essential properties of its own.
Identifying relationship type is a title for relationship type that relates one weak r entity type to one owner entity type. In this relationship type, weak entity has a total participation constraint, meaning it cannot exist without its owner entity type that identifies it.
Partial key (or discriminator) is an attribute or set of attributes of a weak entity type that distinguishes weak entities related to the same owner entity type.

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