SAConnection conn = new SAConnection("DSN=SQL Anywhere 12 Demo");
conn.Open();
SACommand cmd = new SACommand( "SELECT * FROM Departments", conn );
IAsyncResult res = cmd.BeginExecuteReader();
// perform other work
// this blocks until the command completes
SADataReader reader = cmd.EndExecuteReader( res );

SAConnection conn = new SAConnection("DSN=SQL Anywhere 12 Demo");
conn.Open();
SACommand cmd = new SACommand( "SELECT * FROM Departments", conn );
IAsyncResult res = cmd.BeginExecuteReader();
while( !res.IsCompleted ) {
    // do other work
}
// this does not block because the command is finished
SADataReader reader = cmd.EndExecuteReader( res );

SAConnection conn = new SAConnection("DSN=SQL Anywhere 12 Demo");
conn.Open();
SACommand cmd = new SACommand( "SELECT * FROM Departments", conn );
IAsyncResult res = cmd.BeginExecuteReader();
// perform other work
WaitHandle wh = res.AsyncWaitHandle;
wh.WaitOne();
// this does not block because the command is finished
SADataReader reader = cmd.EndExecuteReader( res );

private void callbackFunction( IAsyncResult ar ) {
    SACommand cmd = (SACommand) ar.AsyncState;
    // this does not block since the command has completed
    SADataReader reader = cmd.EndExecuteReader();
}

// elsewhere in the code
private void DoStuff() {
    SAConnection conn = new SAConnection("DSN=SQL Anywhere 12 Demo");
    conn.Open();
    SACommand cmd = new SACommand( "SELECT * FROM Departments", conn );
    IAsyncResult res = cmd.BeginExecuteReader( callbackFunction, cmd );
    // perform other work.  The callback function will be
    // called when the command completes
}