DataTable.ColumnChanged-Ereignis
Tritt ein, nachdem ein Wert für die angegebene DataColumn in einer DataRow geändert wurde.
Namespace: System.Data
Assembly: System.Data (in system.data.dll)
Syntax
'Declaration
Public Event ColumnChanged As DataColumnChangeEventHandler
'Usage
Dim instance As DataTable
Dim handler As DataColumnChangeEventHandler
AddHandler instance.ColumnChanged, handler
public event DataColumnChangeEventHandler ColumnChanged
public:
event DataColumnChangeEventHandler^ ColumnChanged {
void add (DataColumnChangeEventHandler^ value);
void remove (DataColumnChangeEventHandler^ value);
}
/** @event */
public void add_ColumnChanged (DataColumnChangeEventHandler value)
/** @event */
public void remove_ColumnChanged (DataColumnChangeEventHandler value)
JScript unterstützt die Verwendung von Ereignissen, aber nicht die Deklaration von neuen Ereignissen.
Hinweise
Weitere Informationen finden Sie unter Arbeiten mit DataTable-Ereignissen.
Beispiel
Private Shared Sub DataTableColumnChanged()
Dim custTable As DataTable = 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
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]);
}
Plattformen
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
.NET Compact Framework
Unterstützt in: 2.0, 1.0
Siehe auch
Referenz
DataTable-Klasse
DataTable-Member
System.Data-Namespace