This enumeration is used to specify two properties of the ForeignKeyConstraint class: ForeignKeyConstraint.UpdateRule and ForeignKeyConstraint.DeleteRule . The value from this enumeration indicates what will happen to the related child rows when a change is made to a parent row. For example, by using a ForeignKeyConstraint.DeleteRule or Cascade , all child rows are removed when the parent row is deleted. If you use SetNull , the foreign key field in the child record is set to a null value. SetDefault restores the default value for the foreign key field; None performs no action . public enum Rule { None = 0 , Cascade = 1 , SetNull = 2 , SetDefault = 3 } HierarchySystem.Object System.ValueType System.Enum(System.IComparable, System.IFormattable , System.IConvertible) Rule Returned ByForeignKeyConstraint.{DeleteRule , UpdateRule} Passed ToForeignKeyConstraint.{DeleteRule , ForeignKeyConstraint( ) , UpdateRule} |