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ForeignKeyConstraint Constructor (String, DataColumn, DataColumn)

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

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

public ForeignKeyConstraint(
	string constraintName,
	DataColumn parentColumn,
	DataColumn childColumn
)

Parameters

constraintName
Type: System.String

The name of the constraint.

parentColumn
Type: System.Data.DataColumn

The parent DataColumn in the constraint.

childColumn
Type: System.Data.DataColumn

The child DataColumn in the constraint.

ExceptionCondition
ArgumentNullException

One or both of the columns is null.

InvalidConstraintException

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 of the module: 
   ' 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 fkeyConstraint As ForeignKeyConstraint

   ' Set parent and child column variables.
   parentColumn = _
       suppliersProducts.Tables("Suppliers").Columns("SupplierID")
   childColumn = _
       suppliersProducts.Tables("Products").Columns("SupplierID")
   fkeyConstraint = New ForeignKeyConstraint( _
       "SupplierFKConstraint", parentColumn, childColumn)

   ' Set various properties of the constraint. 
   With fkeyConstraint
      .DeleteRule = Rule.SetNull
      .UpdateRule = Rule.Cascade
      .AcceptRejectRule = AcceptRejectRule.Cascade
   End With 

   ' Add the constraint, and set EnforceConstraints to true.
   suppliersProducts.Tables("Products").Constraints.Add(fkeyConstraint)
   suppliersProducts.EnforceConstraints = True 
End Sub

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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