ITPEC IP April 2022 Question 29
ITPEC IP April 2022 — Question 29 of 100
A primary key is specified so that every record in a table can be uniquely identified. Each primary-key value must be unique, and primary-key columns cannot be null. These constraints ensure that one key value identifies exactly one row and provides a reliable target for relationships from other tables.
Answer (d)
Why not others:
- (a) whether data participates in arithmetic is determined by its meaning and type, not by a primary key
- (b) searching may be accelerated by an index, but search capability is not the defining purpose of a primary key
- (c) other tables are allowed to reference a primary key through foreign keys
Key rule: A primary key enforces unique row identity; a foreign key uses that identity to establish a relationship.
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