ITPEC IP October 2024 Question 28
ITPEC IP October 2024 — Question 28 of 100
A single table can define multiple foreign keys, each representing a relationship to a referenced key. For example, an Order table may contain CustomerID referencing Customer and ProductID referencing Product. A foreign key can also consist of multiple columns when it references a compatible composite key.
Answer (c)
Why not others:
- (a) referential integrity, not uniqueness, is the defining constraint of a foreign key
- (b) duplicate foreign-key values are normally allowed because many child rows can reference the same parent
- (d) multiple fields can collectively form one composite foreign key
Key rule: A foreign key requires each non-null referencing value or value combination to match an eligible key in the parent table; it need not be unique in the child table.
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