' 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 null values when a value is deleted.
fkeyConstraint.DeleteRule = Rule.SetNull
fkeyConstraint.UpdateRule = Rule.Cascade
fkeyConstraint.AcceptRejectRule = AcceptRejectRule.Cascade
' Add the constraint, and set EnforceConstraints to true.
suppliersProducts.Tables("Products").Constraints.Add(fkeyConstraint)
suppliersProducts.EnforceConstraints = True
End Sub