nodejs同步調(diào)用獲取mysql數(shù)據(jù)時遇到的大坑

var _getUser = function(name) {
 var sql = "SELECT * FROM " + TABLE + " WHERE user_loginname='" + name + "'";
 connection.query(sql, function(err, results) {
 if(!err) {
 var res = hasUser(results);
 return res;
 }else {
 return error();
 }
 });
 function hasUser(results) {
 if(results.length == 0) {
 return {err: 1, msg: "此用戶名不存在"};
 }
 else {
 return results[0];
 }
 }
 function error() {
 return {err: 1, msg: "數(shù)據(jù)庫出錯"};
 }
}
var getUser = function(name){
 return _getUser(name);
}

//獲取post上來的 data數(shù)據(jù)中 uname的值
var uname = req.body.uname; 
var User = getUser(uname);
if(User.err){
 res.status(404)
 } else {
 var upwd = md5 (req.body.upwd);
 //查詢到匹配用戶名的信息，但相應(yīng)的password屬性不匹配
 if(upwd != User.user_passwd){ 
 req.session.error = "密碼錯誤";
 res.send(404);
 // res.redirect("/login");
 }else{ 
 //信息匹配成功，則將此對象（匹配到的user) 賦給session.user 并返回成功 
 req.session.user = {name: uname, password: upwd};
 res.status(200).send("success")
 // res.send(200);
 // res.redirect("/home");
 }
 }
// md5方式加密
function md5 (text) {
 return crypto.createHash('md5').update(text).digest('hex');
};

var _getUser = function(name, callback) {
 var sql = "SELECT * FROM " + TABLE + " WHERE user_loginname='" + name + "'";
 connection.query(sql, function(err, results) {
 if(!err) {
 var res = hasUser(results)
 callback(res);
 }else {
 callback(error());
 }
 });
 function hasUser(results) {
 if(results.length == 0) {
 return {err: 1, msg: "此用戶名不存在"};
 }
 else {
 return results[0];
 }
 }
 function error() {
 return {err: 1, msg: "數(shù)據(jù)庫出錯"};
 }
}
var getUser = function(name, callback){
 return _getUser(name, callback);
}

//獲取post上來的 data數(shù)據(jù)中 uname的值
var uname = req.body.uname; 
getUser(uname, function(data){
 var User = data;
 if(User.err){
 res.status(404)
 } else {
 var upwd = md5 (req.body.upwd);
 //查詢到匹配用戶名的信息，但相應(yīng)的password屬性不匹配
 if(upwd != User.user_passwd){ 
 req.session.error = "密碼錯誤";
 res.send(404);
 // res.redirect("/login");
 }else{ 
 //信息匹配成功，則將此對象（匹配到的user) 賦給session.user 并返回成功 
 req.session.user = {name: uname, password: upwd};
 res.status(200).send("success")
 // res.send(200);
 // res.redirect("/home");
 }
 }
});
// md5方式加密
function md5 (text) {
 return crypto.createHash('md5').update(text).digest('hex');
};