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 System.Data.dll)

public ForeignKeyConstraint(
	DataColumn parentColumn,
	DataColumn childColumn


Type: System.Data.DataColumn

The parent DataColumn in the constraint.

Type: System.Data.DataColumn

The child DataColumn in the constraint.

Exception Condition

One or both of the columns is null.


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

.NET Framework
Available since 1.1
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