Which key is chosen to serve as a table’s designated unique row identifier?
2026
Which key is chosen to serve as a table’s designated unique row identifier?
Answer: B. Primary Key — ConceptA superkey is any set of attributes that uniquely identifies a row. A candidate key is a minimal superkey: removing any attribute destroys that…
- A.
Foreign Key
- B.
Primary Key
- C.
Candidate Key
- D.
Super Key
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Show answer & explanation
Correct answer: B
Concept
A superkey is any set of attributes that uniquely identifies a row. A candidate key is a minimal superkey: removing any attribute destroys that uniqueness.
One candidate key is designated as the primary key. It becomes the table’s main row identifier and must remain unique and non-null.
Application
The wording asks for the key chosen as the table’s designated unique row identifier. That role is performed by the primary key.
Contrast
Foreign Key: links rows through a reference to a key in another or the same table.
Candidate Key: names every minimal attribute set capable of unique identification; more than one may exist.
Super Key: names every uniquely identifying attribute set, including sets with redundant attributes.
Cross-check
If a table has multiple minimal unique identifiers, only the one selected as the main identifier is called the primary key. Therefore, the required value is Primary Key.