Which of the following best describes the ON DELETE NO ACTION referential integrity constraint?
Which of the following best describes the ON DELETE NO ACTION referential integrity constraint?
The ON DELETE NO ACTION referential integrity constraint ensures that if a parent key is being referenced by any child keys in a database, the record containing the parent key cannot be deleted. This constraint helps maintain data integrity by preventing the deletion of a parent record if there are still dependent child records linked to it.
The ON DELETE NO ACTION referential integrity constraint ensures that if any child keys reference a parent key in a relational database, the record containing the parent key cannot be deleted until all references to it have been removed or updated. This constraint prevents the deletion of a parent record if there are any dependent child records associated with it.
ON DELETE NO ACTION and ON UPDATE CASCADE are two different referential integrity actions in a relational database management system (RDBMS) that are defined when creating or modifying foreign key constraints between tables. ON DELETE NO ACTION: With this option, when a row in the parent (referenced) table is attempted to be deleted, the RDBMS will check if there are any child (referencing) rows in the related table(s). If there are any child rows, the delete action will be restricted, and an error will be raised. This ensures that you cannot delete a parent row if there are dependent child rows.
ON UPDATE CASCADE: With this option, if a row in the parent table is updated and the value of the referenced column changes, the RDBMS will automatically update all corresponding referencing rows in the child table(s) with the new value. This ensures that changes in the parent's primary key values are propagated to the child tables, maintaining data integrity. In summary, ON DELETE NO ACTION prevents deletion of a parent row if there are dependent child rows, while ON UPDATE CASCADE automatically updates the referencing rows in child tables when the referenced primary key value is updated
Answer is C. When the default of ON DELETE NO ACTION is used, the parent record cannot successfully be deleted if a child record is referencing it.