Respuesta :

mominetti

Answer:

By definition a foreign key of table A is a primary key of another table B, thereby establishing a link between them.

To provide referential integrity you can use these referential actions:

  • Cascade: If rows in table B are deleted, the matching foreign key columns in table A are deleted.
  • Set Null: If rows in table B are deleted, the matching foreign key columns in table A are set to null.
  • Set Default: If rows in table B are deleted, the matching foreign key columns in table A are set with the default value of the column.
  • Restrict: A value in table B cannot be deleted or updated while as it is referred to by a foreign key in table A.

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