Which statement describes Delete Set-to-Default?

Which statement describes Delete Set-to-Default?

• A. Deleting a parent deletes child records.
• B. On delete of parent, referencing foreign keys are set to their default values.
• C. It sets the foreign key values to NULL.
• D. It prevents deleting the parent.

Answer: (B)

Delete Set-to-Default is a referential action for a foreign key. When a row in the parent table is deleted, the foreign key values in the related child rows are replaced with their defined default values, rather than deleting the child rows or setting the keys to NULL or blocking the delete. This requires that the child foreign key column has a default value defined; otherwise the action can’t be applied and the delete may fail or be governed by other rules. For example, if a child table has a foreign key with a default value of 0, deleting a parent row would set the child rows’ foreign key to 0. This differs from deleting cascade (which removes children), setting to NULL (ON DELETE SET NULL), or preventing deletion (ON DELETE RESTRICT/NO ACTION).

Delete Set-to-Default is a referential action for a foreign key. When a row in the parent table is deleted, the foreign key values in the related child rows are replaced with their defined default values, rather than deleting the child rows or setting the keys to NULL or blocking the delete. This requires that the child foreign key column has a default value defined; otherwise the action can’t be applied and the delete may fail or be governed by other rules. For example, if a child table has a foreign key with a default value of 0, deleting a parent row would set the child rows’ foreign key to 0. This differs from deleting cascade (which removes children), setting to NULL (ON DELETE SET NULL), or preventing deletion (ON DELETE RESTRICT/NO ACTION).