SqlDataSource.Deleting SqlDataSource.Deleting SqlDataSource.Deleting SqlDataSource.Deleting Event

Definition

Tritt vor einem Löschvorgang ein.Occurs before a delete operation.

public:
 event System::Web::UI::WebControls::SqlDataSourceCommandEventHandler ^ Deleting;
public event System.Web.UI.WebControls.SqlDataSourceCommandEventHandler Deleting;
member this.Deleting : System.Web.UI.WebControls.SqlDataSourceCommandEventHandler 
Public Custom Event Deleting As SqlDataSourceCommandEventHandler 

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie das Deleting -Ereignis behandelt wird, das Delete vor dem Auftreten eines-Vorgangs ausgelöst wird.The following code example demonstrates how to handle the Deleting event that is raised before a Delete operation occurs. Da in diesem Beispiel Daten aus der Northwind-Datenbank gelöscht OnDeleting werden, wird ein-Handler hinzugefügt, um zu versuchen, die Delete Datenbank auf dem Datenträger zu sichern, bevor der Vorgang ausgeführt wird.Because this example deletes data from the Northwind database, an OnDeleting handler is added to attempt to back up the database to disk before the Delete operation is performed.

<%@Page  Language="C#" %>
<%@Import Namespace="System.Data.SqlClient" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
private void OnRecordDeleting(Object source, SqlDataSourceCommandEventArgs e) {    
    // Cancel the delete operation if the checkbox is not checked.
    if (! CheckBox1.Checked) {
        e.Cancel = true;
        Label1.Text = "The command was cancelled because the CheckBox was not checked.";
    }
 }

private void OnRecordDeleted(object source, SqlDataSourceStatusEventArgs e) {
    Label1.Text = e.AffectedRows + " row(s) were deleted";
}
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">
        <asp:SqlDataSource
            id="SqlDataSource1"
            runat="server"
            DataSourceMode="DataSet"
            ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
            SelectCommand="SELECT * FROM Orders"            
            DeleteCommand="DELETE FROM [Order Details] WHERE OrderID=@OrderID;DELETE FROM Orders WHERE OrderID=@OrderID;"
            OnDeleting="OnRecordDeleting"
            OnDeleted="OnRecordDeleted">
        </asp:SqlDataSource>
        <br />
       <asp:CheckBox 
         id="CheckBox1" 
         runat="server"
         autopostback="true"
         text="Check To Delete Data" />
        <br />
        <br />

        <asp:GridView
            id="GridView1"
            runat="server"
            AutoGenerateColumns="False"
            DataKeyNames="OrderID"
            AutoGenerateDeleteButton="True"
            AllowPaging="True"
            PageSize="20"
            DataSourceID="SqlDataSource1">
            <Columns>
                <asp:BoundField HeaderText="Order ID" DataField="OrderID" />
                <asp:BoundField HeaderText="Customer" DataField="CustomerID" />
                <asp:BoundField HeaderText="Order Placed" DataField="OrderDate" />
                <asp:BoundField HeaderText="Order Shipped" DataField="ShippedDate" />
            </Columns>
        </asp:GridView>

        <asp:Label
            id="Label1"
            runat="server">
        </asp:Label>

    </form>
  </body>
</html>
<%@Page  Language="VB" %>
<%@Import Namespace="System.Data.SqlClient" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
 Sub On_Record_Deleting(ByVal source As Object, ByVal e As SqlDataSourceCommandEventArgs)
     ' Cancel the delete operation if the checkbox is not checked.
     If Not CheckBox1.Checked 
            e.Cancel = True
            Label1.Text = "The command was cancelled because the CheckBox was not checked."
     End If

End Sub 'On_Record_Deleting

Sub On_Record_Deleted(ByVal source As Object, ByVal e As SqlDataSourceStatusEventArgs)
    Label1.Text = e.AffectedRows & " row(s) were deleted"

End Sub
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">

        <asp:SqlDataSource
            id="SqlDataSource1"
            runat="server"
            DataSourceMode="DataSet"
            ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
            SelectCommand="SELECT * FROM Orders"
            DeleteCommand="DELETE FROM [Order Details] WHERE OrderID=@OrderID;DELETE FROM Orders WHERE OrderID=@OrderID;"
            OnDeleting="On_Record_Deleting"
            OnDeleted="On_Record_Deleted">
        </asp:SqlDataSource>
        <br />

       <asp:CheckBox 
         id="CheckBox1" 
         runat="server"
         autopostback="true"
         text="Check To Delete Data" />
        <br />
        <br />

        <asp:GridView
            id="GridView1"
            runat="server"
            AutoGenerateColumns="False"
            DataKeyNames="OrderID"
            AutoGenerateDeleteButton="True"
            AllowPaging="True"
            PageSize="20"
            DataSourceID="SqlDataSource1">
            <Columns>
                <asp:BoundField HeaderText="Order ID" DataField="OrderID" />
                <asp:BoundField HeaderText="Customer" DataField="CustomerID" />
                <asp:BoundField HeaderText="Order Placed" DataField="OrderDate" />
                <asp:BoundField HeaderText="Order Shipped" DataField="ShippedDate" />
            </Columns>
        </asp:GridView>

        <asp:Label
            id="Label1"
            runat="server">
        </asp:Label>

    </form>
  </body>
</html>

Hinweise

Behandeln Sie Deleting das-Ereignis, um zusätzliche Initialisierungs Vorgänge auszuführen, die für Ihre Anwendung spezifisch sind, um die Werte von Parametern zu überprüfen oder um SqlDataSource die Parameterwerte zu ändern, bevor das-Steuerelement den Löschvorgang ausführt.Handle the Deleting event to perform additional initialization operations that are specific to your application, to validate the values of parameters, or to change the parameter values before the SqlDataSource control performs the delete operation.

Die Verbindung mit der zugrunde liegenden Datenquelle ist noch nicht geöffnet, wenn der Ereignishandlerdelegat aufgerufen wird.The connection to the underlying data source is not yet open when the event handler delegate is called. Daher können Sie den Vorgang nicht direkt abbrechen, indem Sie Cancel die-Methode DbCommand für das-Objekt aufrufen, SqlDataSourceCommandEventArgs das durch das-Objekt verfügbar gemacht wird.Therefore, you cannot cancel the operation directly by calling the Cancel method on the DbCommand object that is exposed by the SqlDataSourceCommandEventArgs object. Sie können den Daten Bank Vorgang jedoch abbrechen, indem Sie die Cancel -Eigenschaft SqlDataSourceCommandEventArgs des-Objekts trueauf festlegen.You can, however, cancel the database operation by setting the Cancel property of the SqlDataSourceCommandEventArgs object to true.

Weitere Informationen zum Behandeln von Ereignissen finden Sie unter behandeln und Auslösen von Ereignissen.For more information about how to handle events, see Handling and Raising Events.

Gilt für:

Siehe auch