ForeignKeyConstraint Class   System.Data Namespace

---

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

[ VB ]
Overloads Public Sub New ( _
   ByVal parentColumn As DataColumn, _
   ByVal childColumn As DataColumn _
)

[ C# ]
public ForeignKeyConstraint (
   DataColumn parentColumn,
   DataColumn childColumn
);

[ C++ ]
public: ForeignKeyConstraint (
   DataColumn* parentColumn,
   DataColumn* childColumn
);

[ JScript ]
public function ForeignKeyConstraint (
   parentColumn : DataColumn,
   childColumn : DataColumn
);

parentColumn

The parent DataColumn in the constraint.

childColumn

The 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 pCol As DataColumn
   Dim cCol As DataColumn
   Dim myFKC As ForeignKeyConstraint
   ' set parent and child column variables.
   pCol = myDataSet.Tables ( "Suppliers" ).Columns ( "SupplierID" )
   cCol = myDataSet.Tables ( "Products" ).Columns ( "SupplieriD" )
   myFKC = New ForeignKeyConstraint ( pCol, cCol )
   ' set various properties of the constraint.
   With myFKC
      .RelationName = "SuppierFKConstraint"
      .DeleteRule = Rule.SetNull
      .UpdateRule = Rule.Cascade
      .AcceptRejectRule = AcceptRejectRule.Cascade
   End With
   ' add the constraint, and set EnforceConstraints to true.
   myDataSet.Tables ( "Suppliers" ).Constraints.Add myFKC
   myDataSet.EnforceConstraints = True
End Sub

ForeignKeyConstraint Members   ForeignKeyConstraint Constructor Overload List

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