class MySQLConnector {

    public synchronized boolean execute(final String queryString) {
        responseCallback = new DefaultPromise<>(eventLoopGroup.next());
        QueryCommandPacket queryCommandPacket = new QueryCommandPacket();
        queryCommandPacket.setQueryString(queryString);
        channel.writeAndFlush(queryCommandPacket);
        return null != waitExpectedResponse(OkPacket.class);
    }

}