SqlDataSource.Updating SqlDataSource.Updating SqlDataSource.Updating SqlDataSource.Updating Event

Definizione

Si verifica prima di un'operazione di aggiornamento.Occurs before an update operation.

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

Esempi

Nell'esempio di codice riportato di seguito viene illustrato come visualizzare i dati recuperati da un database DropDownList di Microsoft SQL Server in un controllo e come TextBox aggiornare il record utilizzando un controllo.The following code example demonstrates how to display data that is retrieved from a Microsoft SQL Server database in a DropDownList control and update the record using a TextBox control. Nell'esempio viene illustrato come è possibile utilizzare DbTransaction un oggetto per aggiungere il contesto di transazione SqlDataSource quando si utilizza il controllo per aggiornare i dati.The example shows how you can use a DbTransaction object to add transaction context when using the SqlDataSource control to update data.

<%@Page  Language="C#" %>
<%@Import Namespace="System.Data" %>
<%@Import Namespace="System.Data.Common" %>
<%@Import Namespace="System.Data.SqlClient" %>
<%@Import Namespace="System.Diagnostics" %>
<!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 On_Click(Object source, EventArgs e) {    
    SqlDataSource1.Update();
 }

 private void OnSqlUpdating(Object source, SqlDataSourceCommandEventArgs e) {
    DbCommand command = e.Command;
    DbConnection cx  = command.Connection;    
    cx.Open();    
    DbTransaction tx = cx.BeginTransaction();
    command.Transaction = tx;
 }

 private void OnSqlUpdated(Object source, SqlDataSourceStatusEventArgs e) {
    DbCommand command = e.Command;
    DbTransaction tx = command.Transaction;
    
    // In this code example the OtherProcessSucceeded variable represents
    // the outcome of some other process that occurs whenever the data is 
    // updated, and must succeed for the data change to be committed. For 
    // simplicity, we set this value to true. 
    bool OtherProcessSucceeded = true;
    
    if (OtherProcessSucceeded) {
        tx.Commit();
        Label2.Text="The record was updated successfully!";
    }
    else {
        tx.Rollback();
        Label2.Text="The record was not updated.";
    }
 }

</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"
          ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
          SelectCommand="SELECT EmployeeID, LastName, Address FROM Employees"
          UpdateCommand="UPDATE Employees SET Address=@Address WHERE EmployeeID=@EmployeeID"
          OnUpdating="OnSqlUpdating"
          OnUpdated ="OnSqlUpdated">
          <UpdateParameters>
              <asp:ControlParameter Name="Address" ControlId="TextBox1" PropertyName="Text"/>
              <asp:ControlParameter Name="EmployeeID" ControlId="DropDownList1" PropertyName="SelectedValue"/>
          </UpdateParameters>
      </asp:SqlDataSource>

      <asp:DropDownList
          id="DropDownList1"
          runat="server"
          DataTextField="LastName"
          DataValueField="EmployeeID"
          DataSourceID="SqlDataSource1">
      </asp:DropDownList>

      <br />
      <asp:Label id="Label1" runat="server" Text="Enter a new address for the selected user."
        AssociatedControlID="TextBox1" />
      <asp:TextBox id="TextBox1" runat="server" />
      <asp:Button id="Submit" runat="server" Text="Submit" OnClick="On_Click" />

      <br /><asp:Label id="Label2" runat="server" Text="" />

    </form>
  </body>
</html>
<%@Page  Language="VB" %>
<%@Import Namespace="System.Data" %>
<%@Import Namespace="System.Data.Common" %>
<%@Import Namespace="System.Diagnostics" %>
<!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_Click(ByVal source As Object, ByVal e As EventArgs)
        SqlDataSource1.Update()
 End Sub 'On_Click

 Sub On_Sql_Updating(ByVal source As Object, ByVal e As SqlDataSourceCommandEventArgs)
     Dim command as DbCommand
     Dim connection as DbConnection
     Dim transaction as DbTransaction
     
     command    = e.Command
     connection = command.Connection     
     connection.Open()     
     transaction = connection.BeginTransaction()
     command.Transaction = transaction
 
 End Sub 'On_Sql_Updating
 
 Sub On_Sql_Updated(ByVal source As Object, ByVal e As SqlDataSourceStatusEventArgs)
 
    Dim command As DbCommand
    Dim transaction As DbTransaction
    
    command = e.Command
    transaction = command.Transaction
    
    ' In this code example the OtherProcessSucceeded variable represents
    ' the outcome of some other process that occurs whenever the data is 
    ' updated, and must succeed for the data change to be committed. For 
    ' simplicity, we set this value to true. 
    Dim OtherProcessSucceeded as Boolean = True
    
    If (OtherProcessSucceeded) Then
        transaction.Commit()
        Label2.Text="The record was updated successfully!"
    Else    
        transaction.Rollback()
        Label2.Text="The record was not updated."
    End If
 End Sub ' On_Sql_Updated
</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"
          ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
          SelectCommand="SELECT EmployeeID, LastName, Address FROM Employees"
          UpdateCommand="UPDATE Employees SET Address=@Address WHERE EmployeeID=@EmployeeID"
          OnUpdating="On_Sql_Updating"
          OnUpdated ="On_Sql_Updated">
          <UpdateParameters>
              <asp:ControlParameter Name="Address" ControlId="TextBox1" PropertyName="Text"/>
              <asp:ControlParameter Name="EmployeeID" ControlId="DropDownList1" PropertyName="SelectedValue"/>
          </UpdateParameters>
      </asp:SqlDataSource>

      <asp:DropDownList
          id="DropDownList1"
          runat="server"
          DataTextField="LastName"
          DataValueField="EmployeeID"
          DataSourceID="SqlDataSource1">
      </asp:DropDownList>

      <br />
      <asp:Label id="Label1" runat="server" Text="Enter a new address for the selected user."
        AssociatedControlID="TextBox1" />
      <asp:TextBox id="TextBox1" runat="server" />
      <asp:Button id="Submit" runat="server" Text="Submit" OnClick="On_Click" />

      <br /><asp:Label id="Label2" runat="server" Text="" />

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

Commenti

Gestire l' Updating evento per eseguire ulteriori operazioni di inizializzazione specifiche per l'applicazione, per convalidare i valori dei parametri o per modificare i valori dei parametri SqlDataSource prima che il controllo esegua l'operazione di aggiornamento.Handle the Updating 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 update operation. La connessione all'origine dati sottostante non è ancora aperta quando viene chiamato il delegato del gestore eventi.The connection to the underlying data source is not yet open when the event handler delegate is called. Non è pertanto possibile annullare direttamente l' Update operazione sul database chiamando il Cancel metodo sull' DbCommand oggetto esposto dall' SqlDataSourceCommandEventArgs oggetto.Therefore, you cannot directly cancel the Update database operation by calling the Cancel method on the DbCommand object that is exposed by the SqlDataSourceCommandEventArgs object. È tuttavia possibile annullare l'operazione sul database impostando la Cancel proprietà SqlDataSourceCommandEventArgs di su true.You can, however, cancel the database operation by setting the Cancel property of the SqlDataSourceCommandEventArgs to true.

Per altre informazioni su come gestire gli eventi, vedere la gestione e generazione di eventi.For more information about how to handle events, see Handling and Raising Events.

Importante

I valori vengono inseriti nei parametri senza convalida, che rappresenta una potenziale minaccia per la sicurezza.Values are inserted into parameters without validation, which is a potential security threat. Utilizzare l' Updating evento per convalidare i valori dei parametri prima di eseguire la query.Use the Updating event to validate parameter values before executing the query. Per altre informazioni, vedere Cenni preliminari sugli attacchi tramite script.For more information, see Script Exploits Overview.

Si applica a

Vedi anche