ForeignKeyConstraint Class   System.Data Namespace

---

Initializes a new instance of the ForeignKeyConstraint class with the specified arrays of parent and child DataColumn objects.

[ VB ]
Overloads Public Sub New ( _
   ByVal parentColumns( ) As DataColumn, _
   ByVal childColumns( ) As DataColumn _
)

[ C# ]
public ForeignKeyConstraint (
   DataColumn [ ] parentColumns,
   DataColumn [ ] childColumns
);

[ C++ ]
public: ForeignKeyConstraint (
   DataColumn* parentColumns [ ],
   DataColumn* childColumns [ ]
);

[ JScript ]
public function ForeignKeyConstraint (
   parentColumns : DataColumn [ ],
   childColumns : DataColumn [ ]
);

parentColumns

An array of parent DataColumn in the constraint.

childColumns

An array of child DataColumn in the constraint.

Exception Type	Condition
ArgumentNullException	Occurs when One or both of the columns is a null reference ( in Visual Basic Nothing ).
InvalidConstraintException	Occurs when the columns have different data types. -Or - The tables do not belong to the same DataSet.

The following example initializes a new ForeignKeyConstraint, sets various of its properties, and adds it to a DataTable object's ConstraintsCollection.

[ VB ] 
' the next line goes into the Declarations section of the module:
' suppliersProducts is a class derived from DataSet.
Private myDataSet As SuppliersProducts 
Private Sub CreateConstraint ( )
   ' declare parent column and child column variables.
   Dim pCols ( 1 ) As DataColumn
   Dim cCols ( 1 ) As DataColumn
   Dim myFKC As ForeignKeyConstraint
   ' set parent and child column variables.
   pCols ( 0 ) = myDataSet.Tables ( "OrderDetails" ).Columns ( "OrderID" )
   pCols ( 1 ) = myDataSet.Tables ( "OrderDetails" ).Columns ( "ProductID" )
   cCols ( 0 ) = myDataSet.Tables ( "Sales" ).Columns ( "OrderID" )
   cCols ( 1 ) = myDataSet.Tables ( "Sales" ).Columns ( "ProductID" )
   myFKC = New ForeignKeyConstraint ( pCols, cCols )
   ' set various properties of the constraint.
   With myFKC
      .RelationName = "ProductSalesOrders"
      .DeleteRule = Rule.SetDefault
      .UpdateRule = Rule.Cascade
      .AcceptRejectRule = AcceptRejectRule.Cascade
   End With
   ' add the constraint, and set EnforceConstraints to true.
   myDataSet.Tables ( "OrderDetails" ).Constraints.Add myFKC
   myDataSet.EnforceConstraints = True
End Sub

ForeignKeyConstraint Members   ForeignKeyConstraint Constructor Overload List

Suggested Reading