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SQL Anywhere 11.0.1 » UltraLite - .NET Programming » UltraLite .NET 2.0 API reference » ULCommand class

 

EndExecuteNonQuery method

Finishes asynchronous execution of a SQL statement.

Syntax
Visual Basic
Public Function EndExecuteNonQuery( _
   ByVal asyncResult As IAsyncResult _
) As Integer
C#
public int EndExecuteNonQuery(
   IAsyncResult asyncResult
);
Parameters
  • asyncResult   The System.IAsyncResult returned by the call to BeginExecuteNonQuery.

Return value

The number of rows affected (the same behavior as ExecuteNonQuery).

Remarks

You must call EndExecuteNonQuery once for every call to BeginExecuteNonQuery. The call must be after BeginExecuteNonQuery has returned. ADO.NET is not thread safe; it is your responsibility to ensure that BeginExecuteNonQuery has returned. The System.IAsyncResult passed to EndExecuteNonQuery must be the same as the one returned from the BeginExecuteNonQuery call that is being completed. It is an error to call EndExecuteNonQuery to end a call to BeginExecuteReader, and vice versa.

If an error occurs while executing the command, the exception is thrown when EndExecuteNonQuery is called.

There are four ways to wait for execution to complete:

Call EndExecuteNonQuery Calling EndExecuteNonQuery blocks until the command completes. For example:

' Visual Basic
Dim cmd As ULCommand = new ULCommand( _
    "UPDATE Departments" _
    + " SET DepartmentName = 'Engineering'" _
    + " WHERE DepartmentID=100", _
    conn _
  )
Dim res As IAsyncResult res = _
  cmd.BeginExecuteNonQuery()
' perform other work
' this will block until the command completes
Dim rowCount As Integer = _
  cmd.EndExecuteNonQuery( res )

// C#
ULCommand cmd = new ULCommand(
    "UPDATE Departments"
    + " SET DepartmentName = 'Engineering'"
    + " WHERE DepartmentID=100",
    conn
  );
IAsyncResult res = cmd.BeginExecuteNonQuery();
// perform other work
// this will block until the command completes
int rowCount = cmd.EndExecuteNonQuery( res );

Poll the IsCompleted property of the IAsyncResult You can poll the IsCompleted property of the IAsyncResult. For example:

' Visual Basic
Dim cmd As ULCommand = new ULCommand( _
    "UPDATE Departments" _
    + " SET DepartmentName = 'Engineering'" _
    + " WHERE DepartmentID=100", _
    conn _
  )
Dim res As IAsyncResult res = _
  cmd.BeginExecuteNonQuery()
While( !res.IsCompleted )
  ' do other work
End While
' this will block until the command completes
Dim rowCount As Integer = _
  cmd.EndExecuteNonQuery( res )

// C#
ULCommand cmd = new ULCommand(
    "UPDATE Departments"
    + " SET DepartmentName = 'Engineering'"
    + " WHERE DepartmentID=100",
    conn
  );
IAsyncResult res = cmd.BeginExecuteNonQuery();
while( !res.IsCompleted ) {
  // do other work
}
// this will block until the command completes
int rowCount = cmd.EndExecuteNonQuery( res );

Use the IAsyncResult.AsyncWaitHandle property to get a synchronization object You can use the IAsyncResult.AsyncWaitHandle property to get a synchronization object, and wait on that. For example:

' Visual Basic
Dim cmd As ULCommand = new ULCommand( _
    "UPDATE Departments" _
    + " SET DepartmentName = 'Engineering'" _
    + " WHERE DepartmentID=100", _
    conn _
  )
Dim res As IAsyncResult res = _
  cmd.BeginExecuteNonQuery()
' perform other work
Dim wh As WaitHandle = res.AsyncWaitHandle
wh.WaitOne()
' this will not block because the command is finished
Dim rowCount As Integer = _
  cmd.EndExecuteNonQuery( res )

// C#
ULCommand cmd = new ULCommand(
    "UPDATE Departments"
    + " SET DepartmentName = 'Engineering'"
    + " WHERE DepartmentID=100",
    conn
  );
IAsyncResult res = cmd.BeginExecuteNonQuery();
// perform other work
WaitHandle wh = res.AsyncWaitHandle;
wh.WaitOne();
// this will not block because the command is finished
int rowCount = cmd.EndExecuteNonQuery( res );

Specify a callback function when calling BeginExecuteNonQuery You can specify a callback function when calling BeginExecuteNonQuery. For example:

' Visual Basic
Private Sub callbackFunction(ByVal ar As IAsyncResult)
  Dim cmd As ULCommand = _
    CType(ar.AsyncState, ULCommand)
  ' this won't block since the command has completed
  Dim rowCount As Integer = _
    cmd.EndExecuteNonQuery( res )
End Sub
' elsewhere in the code
Private Sub DoStuff() 
  Dim cmd As ULCommand = new ULCommand( _
      "UPDATE Departments" _
      + " SET DepartmentName = 'Engineering'" _
      + " WHERE DepartmentID=100", _
      conn _
    )
  Dim res As IAsyncResult = _
    cmd.BeginExecuteNonQuery( _
        callbackFunction, cmd _
      )
  ' perform other work.  The callback function 
  ' will be called when the command completes
End Sub
// C#
private void callbackFunction( IAsyncResult ar )
{
  ULCommand cmd = (ULCommand) ar.AsyncState;
  // this won't block since the command has completed
  int rowCount = cmd.EndExecuteNonQuery();
}
// elsewhere in the code
private void DoStuff() 
{
  ULCommand cmd = new ULCommand(
      "UPDATE Departments"
      + " SET DepartmentName = 'Engineering'"
      + " WHERE DepartmentID=100",
      conn
    );
  IAsyncResult res = cmd.BeginExecuteNonQuery(
      callbackFunction, cmd
    );
  // perform other work.  The callback function 
  // will be called when the command completes
}

The callback function executes in a separate thread, so the usual caveats related to updating the user interface in a threaded program apply.

See also