DataTable.ColumnChanged Evento

Definizione

Spazio dei nomi:

System.Data

Assembly:

System.Data.Common.dll

Source:

DataTable.cs

Viene generato una volta modificato il valore per l'oggetto DataColumn specificato in un oggetto DataRow.

public:
 event System::Data::DataColumnChangeEventHandler ^ ColumnChanged;

public event System.Data.DataColumnChangeEventHandler? ColumnChanged;

member this.ColumnChanged : System.Data.DataColumnChangeEventHandler 

Public Custom Event ColumnChanged As DataColumnChangeEventHandler 

Tipo evento

DataColumnChangeEventHandler

Esempio

private static void DataTableColumnChanged()
{
    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 ColumnChanged event handler for the table.
    custTable.ColumnChanged += new
        DataColumnChangeEventHandler(Column_Changed );

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

    custTable.AcceptChanges();

    // 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_Changed(object sender, DataColumnChangeEventArgs e )
{
    Console.WriteLine("Column_Changed Event: name={0}; Column={1}; original name={2}",
        e.Row["name"], e.Column.ColumnName, e.Row["name", DataRowVersion.Original]);
}

Private Shared Sub DataTableColumnChanged()
    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 ColumnChanged event handler for the table.
    AddHandler custTable.ColumnChanged, _
        New DataColumnChangeEventHandler(AddressOf Column_Changed )


    ' 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) })
    Next
    
    custTable.AcceptChanges()

    ' 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"))
    Next

End Sub

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

Commenti

Per altre informazioni, vedere Gestione degli eventi DataTable.

Vedi anche

• DataColumnChangeEventHandler
• DataTables