Which of the following constraints is used to enforce referential integrity?

The correct answer is B. Foreign key. A foreign key enforces referential integrity by linking a column in one table to the primary key of another table, ensuring that a value in the child table must exist in the parent table - preventing orphaned records. A (Surrogate key) is not a constraint type at all; it's a…

Database Fundamentals

Question

Options

ASurrogate key
BForeign key
CUnique key
DPrimary key

How the community answered

(30 responses)

A
3% (1)
B
87% (26)
C
7% (2)
D
3% (1)

Explanation

A foreign key enforces referential integrity by linking a column in one table to the primary key of another table, ensuring that a value in the child table must exist in the parent table - preventing orphaned records.

A (Surrogate key) is not a constraint type at all; it's a synthetic identifier (like an auto-incremented ID) used as a primary key, with no referential role.
C (Unique key) ensures no duplicate values in a column but says nothing about relationships between tables.
D (Primary key) uniquely identifies rows within its own table but does not enforce relationships to other tables - that's the foreign key's job.

Memory tip: Think "foreign = from another country." A foreign key points outward to another table, so it's the one that enforces the relationship (integrity) between tables.

Topics

#Foreign key constraint#Referential integrity#Database constraints

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