ITPEC FE Morning October 2022 Question 26

Source exam: ITPEC FE Morning October 2022Topic: Databases

ITPEC FE Morning October 2022 — Question 26 of 80

Foreign Key Purpose — referential integrity between related tables.

A foreign key ensures that a value in a child table always references an existing record in the parent table.

  • •Example: orders.customer_id → customers.id — cannot insert an order for a non-existent customer
  • •Enforces: INSERT and UPDATE are rejected if the referenced row doesn't exist; DELETE of a parent row is blocked (or cascaded)

Why not others:
- (a) Prevent fragmentation — physical storage concern, unrelated to foreign keys
- (c) Restore records after failure — handled by backup/recovery mechanisms
- (d) Speed up searching by co-location — relates to indexing or clustering, not foreign keys

Key rule: Foreign key = referential integrity constraint between parent and child tables.

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