Which column(s) is/are strictly required in a properly designed relational table from a logical modeling perspective?

Difficulty: Easy

Correct Answer: A primary key

Explanation:


Introduction / Context:
Every relation (table) should have a way to uniquely identify each row. This uniqueness requirement underpins keys, indexing, and referential integrity.



Given Data / Assumptions:

  • The question asks what is required in a table design.
  • We are considering logical design best practice (and most physical implementations).


Concept / Approach:
A primary key is the designated candidate key that uniquely identifies each row. While a surrogate key is a common implementation of a primary key, it is not required specifically—natural keys can serve. Foreign keys and alternate keys are optional depending on relationships and additional uniqueness needs.



Step-by-Step Solution:

Recognize the core requirement: unique identification of rows.Map this to “primary key.”Pick “A primary key.”


Verification / Alternative check:
Normalization theory and most DBMS tools expect a primary key for each base table to ensure integrity and support indexing.



Why Other Options Are Wrong:
Foreign key: Only required if the table participates as child in a relationship.
Alternate key: Useful but optional.
Surrogate key: One way to implement a primary key, but not mandatory.



Common Pitfalls:
Assuming every primary key must be surrogate; sometimes a stable natural key is better.



Final Answer:
A primary key

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