DataTable.ColumnChanging Event


Occurs when a value is being changed for the specified DataColumn in a DataRow.

 event System::Data::DataColumnChangeEventHandler ^ ColumnChanging;
public event System.Data.DataColumnChangeEventHandler ColumnChanging;
member this.ColumnChanging : System.Data.DataColumnChangeEventHandler 
Public Custom Event ColumnChanging As DataColumnChangeEventHandler 


private static void DataTableColumnChanging()
    DataTable custTable = new DataTable("Customers");
    // add columns
    custTable.Columns.Add("id", typeof(int));
    custTable.Columns.Add("name", typeof(string));
    custTable.Columns.Add("address", typeof(string));

    // set PrimaryKey
    custTable.Columns[ "id" ].Unique = true;
    custTable.PrimaryKey = new DataColumn[] { custTable.Columns["id"] };

    // add a ColumnChanging event handler for the table.
    custTable.ColumnChanging += new 
        DataColumnChangeEventHandler(Column_Changing );

    // add ten rows
    for(int id=1; id<=10; id++)
            new object[] { id, string.Format(
            "customer{0}", id), string.Format("address{0}", id) });


    // change the name column in all the rows
    foreach(DataRow row in custTable.Rows )
        row["name"] = string.Format("vip{0}", row["id"]);


private static void Column_Changing(object sender, 
    DataColumnChangeEventArgs e )
        "Column_Changing Event: name={0}; Column={1}; proposed name={2}", 
        e.Row["name"], e.Column.ColumnName, e.ProposedValue );
Private Shared Sub DataTableColumnChanging()
    Dim custTable As New DataTable("Customers")
    ' add columns
    custTable.Columns.Add("id", Type.GetType("System.Int32"))
    custTable.Columns.Add("name", Type.GetType("System.String"))
    custTable.Columns.Add("address", Type.GetType("System.String"))

    ' set PrimaryKey
    custTable.Columns("id").Unique = true
    custTable.PrimaryKey = New DataColumn() { custTable.Columns("id") }

    ' add a ColumnChanging event handler for the table.
    AddHandler custTable.ColumnChanging, New _
        DataColumnChangeEventHandler(AddressOf Column_Changing )

    ' add ten rows
    Dim id As Integer
    For id = 1 To 10
        custTable.Rows.Add( _
            New Object() { id, string.Format("customer{0}", id), _
                string.Format("address{0}", id) })

    ' change the name column in all the rows
    Dim row As DataRow
    For Each row In custTable.Rows 
        row("name") = string.Format("vip{0}", row("id"))

End Sub

Private Shared Sub Column_Changing(sender As Object, _
    e As DataColumnChangeEventArgs)
    Console.WriteLine( _
        "Column_Changing Event: name={0}; Column={1}; proposed name={2}", _
        e.Row("name"), e.Column.ColumnName, e.ProposedValue) 
End Sub


For more information, see Handling DataTable Events.

Applies to

See also