SqlCommand.BeginExecuteNonQuery 方法
定义
重要
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启动由此描述 SqlCommand的 Transact-SQL 语句或存储过程的异步执行。
重载
| 名称 | 说明 |
|---|---|
| BeginExecuteNonQuery() |
启动由此描述 SqlCommand的 Transact-SQL 语句或存储过程的异步执行。 |
| BeginExecuteNonQuery(AsyncCallback, Object) |
根据回调过程和状态信息，启动由此 SqlCommand描述的 Transact-SQL 语句或存储过程的异步执行。 |
BeginExecuteNonQuery()
启动由此描述 SqlCommand的 Transact-SQL 语句或存储过程的异步执行。
public:
IAsyncResult ^ BeginExecuteNonQuery();public IAsyncResult BeginExecuteNonQuery();member this.BeginExecuteNonQuery : unit -> IAsyncResultPublic Function BeginExecuteNonQuery () As IAsyncResult返回
一个 IAsyncResult 可用于轮询或等待结果或两者的结果;调用 EndExecuteNonQuery(IAsyncResult)时也需要此值，这将返回受影响的行数。
例外
如果设置为 Stream，则使用Value二进制或 VarBinary 以外的其他SqlDbType项。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
-或-
设置为
-或-
名称/值对“异步处理=true”不包括在定义此 SqlCommand连接的连接字符串中。
-或-
在 SqlConnection 流式处理操作期间关闭或删除。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
流式处理操作期间发生错误StreamXmlReader或TextReader对象。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
XmlReader TextReader流式处理操作期间关闭或Stream对象。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
示例
以下控制台应用程序在 AdventureWorks 示例数据库中创建更新数据，以异步方式执行其工作。 为了模拟长时间运行的进程，此示例在命令文本中插入一个 WAITFOR 语句。 通常，你不会努力使命令运行速度较慢，但在这种情况下执行此操作可以更轻松地演示异步行为。
using System.Data.SqlClient;
class Class1
{
static void Main()
{
// This is a simple example that demonstrates the usage of the
// BeginExecuteNonQuery functionality.
// The WAITFOR statement simply adds enough time to prove the
// asynchronous nature of the command.
string commandText =
"UPDATE Production.Product SET ReorderPoint = ReorderPoint + 1 " +
"WHERE ReorderPoint Is Not Null;" +
"WAITFOR DELAY '0:0:3';" +
"UPDATE Production.Product SET ReorderPoint = ReorderPoint - 1 " +
"WHERE ReorderPoint Is Not Null";
RunCommandAsynchronously(commandText, GetConnectionString());
Console.WriteLine("Press ENTER to continue.");
Console.ReadLine();
}
private static void RunCommandAsynchronously(
string commandText, string connectionString)
{
// Given command text and connection string, asynchronously execute
// the specified command against the connection. For this example,
// the code displays an indicator as it is working, verifying the
// asynchronous behavior.
using (SqlConnection connection =
new SqlConnection(connectionString))
{
try
{
int count = 0;
SqlCommand command = new SqlCommand(commandText, connection);
connection.Open();
IAsyncResult result = command.BeginExecuteNonQuery();
while (!result.IsCompleted)
{
Console.WriteLine("Waiting ({0})", count++);
// Wait for 1/10 second, so the counter
// does not consume all available resources
// on the main thread.
System.Threading.Thread.Sleep(100);
}
Console.WriteLine("Command complete. Affected {0} rows.",
command.EndExecuteNonQuery(result));
}
catch (SqlException ex)
{
Console.WriteLine("Error ({0}): {1}", ex.Number, ex.Message);
}
catch (InvalidOperationException ex)
{
Console.WriteLine("Error: {0}", ex.Message);
}
catch (Exception ex)
{
// You might want to pass these errors
// back out to the caller.
Console.WriteLine("Error: {0}", ex.Message);
}
}
}
private static string GetConnectionString()
{
// To avoid storing the connection string in your code,
// you can retrieve it from a configuration file.
// If you have not included "Asynchronous Processing=true" in the
// connection string, the command is not able
// to execute asynchronously.
return "Data Source=(local);Integrated Security=SSPI;" +
"Initial Catalog=AdventureWorks; Asynchronous Processing=true";
}
}
Imports System.Data.SqlClient
Module Module1
Sub Main()
' This is a simple example that demonstrates the usage of the
' BeginExecuteNonQuery functionality.
' The WAITFOR statement simply adds enough time to prove the
' asynchronous nature of the command.
Dim commandText As String =
"UPDATE Production.Product SET ReorderPoint = ReorderPoint + 1 " &
"WHERE ReorderPoint Is Not Null;" &
"WAITFOR DELAY '0:0:3';" &
"UPDATE Production.Product SET ReorderPoint = ReorderPoint - 1 " &
"WHERE ReorderPoint Is Not Null"
RunCommandAsynchronously(commandText, GetConnectionString())
Console.WriteLine("Press ENTER to continue.")
Console.ReadLine()
End Sub
Private Sub RunCommandAsynchronously(
ByVal commandText As String, ByVal connectionString As String)
' Given command text and connection string, asynchronously execute
' the specified command against the connection. For this example,
' the code displays an indicator as it is working, verifying the
' asynchronous behavior.
Using connection As New SqlConnection(connectionString)
Try
Dim count As Integer = 0
Dim command As New SqlCommand(commandText, connection)
connection.Open()
Dim result As IAsyncResult = command.BeginExecuteNonQuery()
While Not result.IsCompleted
Console.WriteLine("Waiting ({0})", count)
' Wait for 1/10 second, so the counter
' does not consume all available resources
' on the main thread.
Threading.Thread.Sleep(100)
count += 1
End While
Console.WriteLine("Command complete. Affected {0} rows.",
command.EndExecuteNonQuery(result))
Catch ex As SqlException
Console.WriteLine("Error ({0}): {1}", ex.Number, ex.Message)
Catch ex As InvalidOperationException
Console.WriteLine("Error: {0}", ex.Message)
Catch ex As Exception
' You might want to pass these errors
' back out to the caller.
Console.WriteLine("Error: {0}", ex.Message)
End Try
End Using
End Sub
Private Function GetConnectionString() As String
' To avoid storing the connection string in your code,
' you can retrieve it from a configuration file.
' If you have not included "Asynchronous Processing=true" in the
' connection string, the command is not able
' to execute asynchronously.
Return "Data Source=(local);Integrated Security=SSPI;" &
"Initial Catalog=AdventureWorks; Asynchronous Processing=true"
End Function
End Module
注解
该方法 BeginExecuteNonQuery 启动异步执行不返回行的 Transact-SQL 语句或存储过程的过程，以便其他任务在执行语句时可以并发运行。 语句完成后，开发人员必须调用 EndExecuteNonQuery 该方法来完成操作。 该方法 BeginExecuteNonQuery 会立即返回，但在代码执行相应的 EndExecuteNonQuery 方法调用之前，它不得执行针对同 SqlCommand 一对象启动同步或异步执行的任何其他调用。 EndExecuteNonQuery在命令的执行完成之前调用该对象会导致SqlCommand对象阻塞，直到执行完成。
请注意，命令文本和参数将同步发送到服务器。 如果发送了大型命令或多个参数，此方法可能会在写入期间阻止。 发送命令后，该方法会立即返回，而无需等待来自服务器的答案，即读取是异步的。
由于此重载不支持回调过程，因此开发人员必须轮询以确定命令是否已完成，使用IsCompleted方法返回BeginExecuteNonQuery的属性IAsyncResult;或使用返回IAsyncResult的属性等待完成一个或多个命令AsyncWaitHandle。
此方法忽略 CommandTimeout 属性。
另请参阅
适用于
BeginExecuteNonQuery(AsyncCallback, Object)
根据回调过程和状态信息，启动由此 SqlCommand描述的 Transact-SQL 语句或存储过程的异步执行。
public:
IAsyncResult ^ BeginExecuteNonQuery(AsyncCallback ^ callback, System::Object ^ stateObject);public IAsyncResult BeginExecuteNonQuery(AsyncCallback callback, object stateObject);member this.BeginExecuteNonQuery : AsyncCallback * obj -> IAsyncResultPublic Function BeginExecuteNonQuery (callback As AsyncCallback, stateObject As Object) As IAsyncResult参数
- callback
- AsyncCallback
命令 AsyncCallback 执行完成后调用的委托。 传入 null （Nothing Microsoft Visual Basic）以指示不需要回调。
- stateObject
- Object
传递给回调过程的用户定义状态对象。 使用 AsyncState 属性从回调过程中检索此对象。
返回
一个 IAsyncResult 可用于轮询或等待结果或两者的结果;调用 EndExecuteNonQuery(IAsyncResult)时也需要此值，这将返回受影响的行数。
例外
如果设置为 Stream，则使用Value二进制或 VarBinary 以外的其他SqlDbType项。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
-或-
设置为
-或-
名称/值对“异步处理=true”不包括在定义此 SqlCommand连接的连接字符串中。
-或-
在 SqlConnection 流式处理操作期间关闭或删除。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
流式处理操作期间发生错误StreamXmlReader或TextReader对象。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
XmlReader TextReader流式处理操作期间关闭或Stream对象。 有关流式处理的详细信息，请参阅 SqlClient 流式处理支持。
示例
以下 Windows 应用程序演示了该方法的使用 BeginExecuteNonQuery ，执行 Transact-SQL 语句，该语句包含几秒钟的延迟（模拟长时间运行的命令）。
此示例演示了许多重要的技术。 这包括从单独的线程调用与表单交互的方法。 此外，此示例演示了如何阻止用户多次并发执行命令，以及如何确保在调用回调过程之前窗体未关闭。
若要设置此示例，请创建新的 Windows 应用程序。 Button将控件和Label控件放在窗体上（接受每个控件的默认名称）。 将以下代码添加到窗体的类，根据需要修改环境的连接字符串。
using System.Data.SqlClient;
namespace Microsoft.AdoDotNet.CodeSamples
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
// Hook up the form's Load event handler (you can double-click on
// the form's design surface in Visual Studio), and then add
// this code to the form's class:
private void Form1_Load(object sender, EventArgs e)
{
this.button1.Click += new System.EventHandler(this.button1_Click);
this.FormClosing += new System.Windows.Forms.
FormClosingEventHandler(this.Form1_FormClosing);
}
// You need this delegate in order to display text from a thread
// other than the form's thread. See the HandleCallback
// procedure for more information.
// This same delegate matches both the DisplayStatus
// and DisplayResults methods.
private delegate void DisplayInfoDelegate(string Text);
// This flag ensures that the user does not attempt
// to restart the command or close the form while the
// asynchronous command is executing.
private bool isExecuting;
// This example maintains the connection object
// externally, so that it is available for closing.
private SqlConnection connection;
private static string GetConnectionString()
{
// To avoid storing the connection string in your code,
// you can retrieve it from a configuration file.
// If you have not included "Asynchronous Processing=true" in the
// connection string, the command is not able
// to execute asynchronously.
return "Data Source=(local);Integrated Security=true;" +
"Initial Catalog=AdventureWorks; Asynchronous Processing=true";
}
private void DisplayStatus(string Text)
{
this.label1.Text = Text;
}
private void DisplayResults(string Text)
{
this.label1.Text = Text;
DisplayStatus("Ready");
}
private void Form1_FormClosing(object sender,
System.Windows.Forms.FormClosingEventArgs e)
{
if (isExecuting)
{
MessageBox.Show(this, "Cannot close the form until " +
"the pending asynchronous command has completed. Please wait...");
e.Cancel = true;
}
}
private void button1_Click(object sender, System.EventArgs e)
{
if (isExecuting)
{
MessageBox.Show(this,
"Already executing. Please wait until the current query " +
"has completed.");
}
else
{
SqlCommand command = null;
try
{
DisplayResults("");
DisplayStatus("Connecting...");
connection = new SqlConnection(GetConnectionString());
// To emulate a long-running query, wait for
// a few seconds before working with the data.
// This command does not do much, but that's the point--
// it does not change your data, in the long run.
string commandText =
"WAITFOR DELAY '0:0:05';" +
"UPDATE Production.Product SET ReorderPoint = ReorderPoint + 1 " +
"WHERE ReorderPoint Is Not Null;" +
"UPDATE Production.Product SET ReorderPoint = ReorderPoint - 1 " +
"WHERE ReorderPoint Is Not Null";
command = new SqlCommand(commandText, connection);
connection.Open();
DisplayStatus("Executing...");
isExecuting = true;
// Although it is not required that you pass the
// SqlCommand object as the second parameter in the
// BeginExecuteNonQuery call, doing so makes it easier
// to call EndExecuteNonQuery in the callback procedure.
AsyncCallback callback = new AsyncCallback(HandleCallback);
command.BeginExecuteNonQuery(callback, command);
}
catch (Exception ex)
{
isExecuting = false;
DisplayStatus(string.Format("Ready (last error: {0})", ex.Message));
if (connection != null)
{
connection.Close();
}
}
}
}
private void HandleCallback(IAsyncResult result)
{
try
{
// Retrieve the original command object, passed
// to this procedure in the AsyncState property
// of the IAsyncResult parameter.
SqlCommand command = (SqlCommand)result.AsyncState;
int rowCount = command.EndExecuteNonQuery(result);
string rowText = " rows affected.";
if (rowCount == 1)
{
rowText = " row affected.";
}
rowText = rowCount + rowText;
// You may not interact with the form and its contents
// from a different thread, and this callback procedure
// is all but guaranteed to be running from a different thread
// than the form. Therefore you cannot simply call code that
// displays the results, like this:
// DisplayResults(rowText)
// Instead, you must call the procedure from the form's thread.
// One simple way to accomplish this is to call the Invoke
// method of the form, which calls the delegate you supply
// from the form's thread.
DisplayInfoDelegate del = new DisplayInfoDelegate(DisplayResults);
this.Invoke(del, rowText);
}
catch (Exception ex)
{
// Because you are now running code in a separate thread,
// if you do not handle the exception here, none of your other
// code catches the exception. Because none of
// your code is on the call stack in this thread, there is nothing
// higher up the stack to catch the exception if you do not
// handle it here. You can either log the exception or
// invoke a delegate (as in the non-error case in this
// example) to display the error on the form. In no case
// can you simply display the error without executing a delegate
// as in the try block here.
// You can create the delegate instance as you
// invoke it, like this:
this.Invoke(new DisplayInfoDelegate(DisplayStatus),
String.Format("Ready(last error: {0}", ex.Message));
}
finally
{
isExecuting = false;
if (connection != null)
{
connection.Close();
}
}
}
}
}
Imports System.Data.SqlClient
Imports System.Windows.Forms
Public Class Form1
' Add this code to the form's class:
' You need this delegate in order to display text from a thread
' other than the form's thread. See the HandleCallback
' procedure for more information.
' This same delegate matches both the DisplayStatus
' and DisplayResults methods.
Private Delegate Sub DisplayInfoDelegate(ByVal Text As String)
' This flag ensures that the user does not attempt
' to restart the command or close the form while the
' asynchronous command is executing.
Private isExecuting As Boolean
' This example maintains the connection object
' externally, so that it is available for closing.
Private connection As SqlConnection
Private Function GetConnectionString() As String
' To avoid storing the connection string in your code,
' you can retrieve it from a configuration file.
' If you have not included "Asynchronous Processing=true" in the
' connection string, the command is not able
' to execute asynchronously.
Return "Data Source=(local);Integrated Security=true;" &
"Initial Catalog=AdventureWorks; Asynchronous Processing=true"
End Function
Private Sub DisplayStatus(ByVal Text As String)
Me.Label1.Text = Text
End Sub
Private Sub DisplayResults(ByVal Text As String)
Me.Label1.Text = Text
DisplayStatus("Ready")
End Sub
Private Sub Form1_FormClosing(ByVal sender As Object,
ByVal e As FormClosingEventArgs) _
Handles Me.FormClosing
If isExecuting Then
MessageBox.Show(Me, "Cannot close the form until " &
"the pending asynchronous command has completed. Please wait...")
e.Cancel = True
End If
End Sub
Private Sub Button1_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles Button1.Click
If isExecuting Then
MessageBox.Show(Me,
"Already executing. Please wait until the current query " &
"has completed.")
Else
Dim command As SqlCommand
Try
DisplayResults("")
DisplayStatus("Connecting...")
connection = New SqlConnection(GetConnectionString())
' To emulate a long-running query, wait for
' a few seconds before working with the data.
' This command does not do much, but that's the point--
' it does not change your data, in the long run.
Dim commandText As String =
"WAITFOR DELAY '0:0:05';" &
"UPDATE Production.Product SET ReorderPoint = ReorderPoint + 1 " &
"WHERE ReorderPoint Is Not Null;" &
"UPDATE Production.Product SET ReorderPoint = ReorderPoint - 1 " &
"WHERE ReorderPoint Is Not Null"
command = New SqlCommand(commandText, connection)
connection.Open()
DisplayStatus("Executing...")
isExecuting = True
' Although it is not required that you pass the
' SqlCommand object as the second parameter in the
' BeginExecuteNonQuery call, doing so makes it easier
' to call EndExecuteNonQuery in the callback procedure.
Dim callback As New AsyncCallback(AddressOf HandleCallback)
command.BeginExecuteNonQuery(callback, command)
Catch ex As Exception
isExecuting = False
DisplayStatus(String.Format("Ready (last error: {0})", ex.Message))
If connection IsNot Nothing Then
connection.Close()
End If
End Try
End If
End Sub
Private Sub HandleCallback(ByVal result As IAsyncResult)
Try
' Retrieve the original command object, passed
' to this procedure in the AsyncState property
' of the IAsyncResult parameter.
Dim command As SqlCommand = CType(result.AsyncState, SqlCommand)
Dim rowCount As Integer = command.EndExecuteNonQuery(result)
Dim rowText As String = " rows affected."
If rowCount = 1 Then
rowText = " row affected."
End If
rowText = rowCount & rowText
' You may not interact with the form and its contents
' from a different thread, and this callback procedure
' is all but guaranteed to be running from a different thread
' than the form. Therefore you cannot simply call code that
' displays the results, like this:
' DisplayResults(rowText)
' Instead, you must call the procedure from the form's thread.
' One simple way to accomplish this is to call the Invoke
' method of the form, which calls the delegate you supply
' from the form's thread.
Dim del As New DisplayInfoDelegate(AddressOf DisplayResults)
Me.Invoke(del, rowText)
Catch ex As Exception
' Because you are now running code in a separate thread,
' if you do not handle the exception here, none of your other
' code catches the exception. Because none of your code
' is on the call stack in this thread, there is nothing
' higher up the stack to catch the exception if you do not
' handle it here. You can either log the exception or
' invoke a delegate (as in the non-error case in this
' example) to display the error on the form. In no case
' can you simply display the error without executing a delegate
' as in the Try block here.
' You can create the delegate instance as you
' invoke it, like this:
Me.Invoke(New DisplayInfoDelegate(AddressOf DisplayStatus),
String.Format("Ready(last error: {0}", ex.Message))
Finally
isExecuting = False
If connection IsNot Nothing Then
connection.Close()
End If
End Try
End Sub
End Class
注解
该方法 BeginExecuteNonQuery 启动异步执行不返回行的 Transact-SQL 语句或存储过程的过程，以便其他任务在执行语句时可以并发运行。 语句完成后，开发人员必须调用 EndExecuteNonQuery 该方法来完成操作。 该方法 BeginExecuteNonQuery 会立即返回，但在代码执行相应的 EndExecuteNonQuery 方法调用之前，它不得执行针对同 SqlCommand 一对象启动同步或异步执行的任何其他调用。 EndExecuteNonQuery在命令的执行完成之前调用该对象会导致SqlCommand对象阻塞，直到执行完成。
通过该 callback 参数，可以指定在 AsyncCallback 语句完成时调用的委托。 可以从此委托过程或应用程序中的任何其他位置调用 EndExecuteNonQuery 该方法。 此外，还可以在参数中 asyncStateObject 传递任何对象，回调过程可以使用该属性检索此信息 AsyncState 。
请注意，命令文本和参数将同步发送到服务器。 如果发送了大型命令或多个参数，此方法可能会在写入期间阻止。 发送命令后，该方法会立即返回，而无需等待来自服务器的答案，即读取是异步的。
由于回调过程从 Microsoft .NET 公共语言运行时提供的后台线程内执行，因此，必须采取严格的方法来处理应用程序中的跨线程交互。 例如，不得从回调过程中与表单的内容进行交互;如果必须更新窗体，必须切换回窗体的线程才能完成工作。 本主题中的示例演示了此行为。
在执行操作期间发生的所有错误都会作为回调过程中的异常引发。 必须在回调过程中处理异常，而不是在主应用程序中处理。 有关在回调过程中处理异常的其他信息，请参阅本主题中的示例。
此方法忽略 CommandTimeout 属性。
