Which of the following constraints enforces that the value of the primary key…
2017
Which of the following constraints enforces that the value of the primary key cannot be Null?
- A.
Key constraint
- B.
Foreign key constraint
- C.
Domain constraint
- D.
Entity integrity constraint
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Correct answer: D
The correct option is D: Entity integrity constraint. The entity integrity constraint is a fundamental rule in the relational database model which strictly states that no primary key value can be NULL. This ensures that every row in a table can be uniquely identified.