Which statement describes Update Cascade?

Which statement describes Update Cascade?

• A. When the primary key is updated, all referencing foreign keys are updated accordingly.
• B. Updates are blocked if there are referencing rows.
• C. Sets referencing keys to NULL on update.
• D. Updates do not affect referencing records.

Answer: (A)

Update Cascade means that when the value of a parent key changes, the database automatically updates all foreign keys in the child rows that reference that parent. This keeps related data consistent and prevents orphaned references. For example, if a department’s primary key changes, every employee referencing that department will have their dept_id updated too. Other behaviors describe non-cascading rules: updates can be blocked if there are referencing rows, or the referencing keys might be set to NULL, or updates might not affect referencing records at all. These do not propagate the change, which is why they aren’t describing update cascade.

Update Cascade means that when the value of a parent key changes, the database automatically updates all foreign keys in the child rows that reference that parent. This keeps related data consistent and prevents orphaned references. For example, if a department’s primary key changes, every employee referencing that department will have their dept_id updated too.

Other behaviors describe non-cascading rules: updates can be blocked if there are referencing rows, or the referencing keys might be set to NULL, or updates might not affect referencing records at all. These do not propagate the change, which is why they aren’t describing update cascade.