ForeignKeyConstraint Constructor (DataColumn, DataColumn)

ForeignKeyConstraint Constructor (DataColumn, DataColumn)

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

Namespace: System.Data
Assembly: System.Data (in

public ForeignKeyConstraint (
	DataColumn parentColumn,
	DataColumn childColumn
public ForeignKeyConstraint (
	DataColumn parentColumn, 
	DataColumn childColumn
public function ForeignKeyConstraint (
	parentColumn : DataColumn, 
	childColumn : DataColumn



The parent DataColumn in the constraint.


The child DataColumn in the constraint.

Exception typeCondition


One or both of the columns is a null reference (Nothing in Visual Basic).


The columns have different data types.

-Or -

The tables don't belong to the same DataSet.

The following example creates a new ForeignKeyConstraint, sets some of its properties, and adds it to a DataTable object's ConstraintCollection.

' The next line goes into the Declarations section.
' SuppliersProducts is a class derived from DataSet.
Private suppliersProducts As SuppliersProducts 
Private Sub CreateConstraint()
   ' Declare parent column and child column variables.
   Dim parentColumn As DataColumn
   Dim childColumn As DataColumn
   Dim fkConstraint As ForeignKeyConstraint

   ' Set parent and child column variables.
   parentColumn = _
   childColumn = _
   fkConstraint = New ForeignKeyConstraint(parentColumn, childColumn)

   ' Set various properties of the constraint.
   With fkConstraint
      .ConstraintName = "suppierFKConstraint"
      .DeleteRule = Rule.SetNull
      .UpdateRule = Rule.Cascade
      .AcceptRejectRule = AcceptRejectRule.Cascade
   End With

   ' Add the constraint, and set EnforceConstraints to true.
   suppliersProducts.EnforceConstraints = True
End Sub

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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