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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: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0
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