In RDBMS, the constraint that no key attribute (column) may be NULL is…
2016
In RDBMS, the constraint that no key attribute (column) may be NULL is referred to as :
- A.
Referential integrity
- B.
Multi-valued dependency
- C.
Entity Integrity
- D.
Functional dependency
Attempted by 1386 students.
Show answer & explanation
Correct answer: C
Answer: Entity Integrity
Definition: Entity Integrity requires that key attributes (typically primary keys) cannot be NULL. This ensures each tuple (row) in a relation can be uniquely identified.
Primary key columns must contain non-NULL values; without this, rows could lack a unique identifier.
Referential integrity concerns foreign keys referencing primary keys in other tables; it does not impose the non-NULL requirement on key attributes.
Functional dependency describes that one attribute determines another; it is a relationship property, not a rule that keys cannot be NULL.
Multi-valued dependency deals with attributes that have multiple independent values and is unrelated to NULL constraints on keys.
Example: In an Employee table with id as the primary key, id cannot be NULL for any row; this is the Entity Integrity constraint in action.
A video solution is available for this question — log in and enroll to watch it.