cascading delete

For relationships that enforce referential integrity between tables, cascading delete is an option that causes the deletion of a record from the primary table to automatically delete all related records in the related foreign table or tables.

For example, if you establish a relationship between a Customers (primary) table and an Orders (foreign) table with the cascading delete option enabled, when a record in the Customers table is deleted, all orders associated with that customer would also be deleted in the foreign Orders table.

Now also definable from SQL DDL.