node.js里用到是node-odbc，通过freetds+unixodbc连接sqlserver

Database=require('odbc').Database,
db=new Database(),
cn="DSN=SERVER;UID=sa;PWD=pwd;DATABASE=db",
iconv=require('iconv-lite');
    http.createServer(function(request, response) {
    response.writeHead(200, {"Content-Type": "text/html;charset=utf-8"});
    db.open(cn,function(err){
    	if(err) return console.log(err);
    
    	db.query("select top 20 usernc from theuser order by userid desc",function(err,rows,moreResultSets){
    		if(err) return console.log(err);
    var a="";
     for (var i in rows) {  
             a+=rows[i].usernc+',';
            console.log(rows[i].usernc);      
        }      
    response.write(a);		    		
    	});   
    
     db.close(function (err) {
            console.log("the database connection is now closed");
        });
    });

输出到中文都是？？？？？？？问号，

而直接用isql -v server sa pwd 查出来到中文能正常显示 用tsql -S server -p 1433 -U sa -P pwd 查出来到也没事，

就用node-odbc 出来的是？？？？？？