NodeJS连接MySQL出现Cannot enqueue Handshake after invoking quit.
原因在于node连接上mysql后如果因网络原因丢失连接或者用户手工关闭连接后，原有的连接挂掉，需要重新连接；如下代码，每次访问结束都关闭，每次开始访问前重连接下，代码中没有监听连接的fatal错误，copy需谨慎

var mysql = require('mysql');var connection = mysql.createConnection({host     : 'localhost',user     : 'root',password : '123456',database : 'test'}),slice = [].slice;var commonMethod = function(callback){connection = mysql.createConnection(connection.config);connection.connect();callback.call(connection,callback);connection.end();};var onerror = function(){console.log(err);};var query = function(){var args = arguments;commonMethod(function(){connection.query.apply(connection,args).on('error',onerror);});};