Cancel
Cancel();
Halts a Command that is currently executing. If
the Command isn’t executing,
nothing happens. If the Command is in the middle
of fetching results with a DataReader, the
DataReader is closed. If the
Command is in the middle of performing another
time-consuming operation, an attempt is made to stop the operation.
However, in this case, the Cancel( ) method must
be called from another thread because the main thread will be
blocked, waiting for the operation to complete.