In ER modeling, which type of entity cannot exist unless another entity exists, yet does not need to include the other entity's identifier as part of its own identifier?

Introduction / Context:
Some child entities require a parent for existence (mandatory relationship) but still have their own identifying key. Understanding the difference between ID-dependent and ID-independent situations determines how you choose primary keys and relationship types in the schema.

Given Data / Assumptions:

• The child cannot exist unless the parent exists (existence-dependent).
• The child's identifier does not include the parent's identifier.
• We seek the term that describes this situation.

Concept / Approach:
An ID-dependent entity uses a primary key that includes its parent's key (identifying relationship). By contrast, an ID-independent entity has its own primary key while still being existence-dependent on the parent (non-identifying relationship with mandatory participation). The prompt explicitly says the child does not require the parent's identifier in its own key, so the child is ID-independent.

Step-by-Step Solution:

Verification / Alternative check:
In Crow’s Foot modeling, this is modeled as a non-identifying relationship (dashed line) with required participation on the child side.

Why Other Options Are Wrong:
Weak entity: Typically implies identifying relationship using the parent’s key (ID-dependent).
Strong entity: Has existence independent of any parent.
ID-dependent entity: Contradicts the prompt because it must include the parent’s identifier.
Associative entity: Resolves many-to-many relationships; not necessarily tied to this key behavior.

Common Pitfalls:
Assuming all existence-dependent entities must be ID-dependent. Existence dependence and identification are related but distinct design choices.

Final Answer:
ID- independent entity