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ConstraintCollection.Add Method (String, DataColumn[], DataColumn[])

Constructs a new ForeignKeyConstraint, with the specified arrays of parent columns and child columns, and adds the constraint to the collection.

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

public Constraint Add(
	string name,
	DataColumn[] primaryKeyColumns,
	DataColumn[] foreignKeyColumns


Type: System.String

The name of the ForeignKeyConstraint.

Type: System.Data.DataColumn[]

An array of DataColumn objects that are the primary key, or parent, columns.

Type: System.Data.DataColumn[]

An array of DataColumn objects that are the foreign key, or child, columns.

The CollectionChanged event occurs if the constraint is added successfully.

The following example creates two arrays of DataColumn objects, and then creates two ForeignKeyConstraint relationships between two tables in a dataset.

private void AddForeignConstraint(
    DataSet dataSet, DataTable table)
        DataColumn[] parentColumns = new DataColumn[2];
        DataColumn[] childColumns = new DataColumn[2];
        // Get the tables from the DataSet.
        DataTable customersTable = dataSet.Tables["Customers"];
        DataTable ordersTable = dataSet.Tables["Orders"];

        // Set Columns.
        childColumns[0] = ordersTable.Columns["CustomerID"];
        childColumns[1] = ordersTable.Columns["CustomerName"];

        // Create ForeignKeyConstraint
            parentColumns, childColumns);
    catch(Exception ex)
        // In case the constraint already exists,  
        // catch the collision here and respond.
        Console.WriteLine("Exception of type {0} occurred.", 

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0