nodejs async无法解决的一个问题

[学无止境-逆流而上]

我想把这3个mysql操作用async优化，流程是第一个查询有数据的话，则后面2个不执行，并return数据。

var findUserByUnPwSql = "select * from user where username = '" + username + "'and password ='" + password + "'";
mysqldb.excute(findUserByUnPwSql, function (results) {
if(results.length>0){
return done(null, false, req.flash('signupMessage', '该用户已存在！'));
}else{
var insertUserSql = "insert into user(username,password) values('" + username + "','" + password + "')";
mysqldb.excute(insertUserSql, function (results) {
mysqldb.excute(findUserByUnPwSql, function (results) {
return done(null, results[0]);
});
});
}
});

[KK3K2005]

function adduser(username, password, callback){ mysqldb.excute(find, function (results) { if(results.length>0){ callback('该用户已存在'); }else{ mysqldb.excute(insert, function (results) { mysqldb.excute(find, function (results) { callback(result); }); }); } } }

[学无止境-逆流而上]

我写出来了，其实想多了，结果直接return就可以，不用考虑怎么怎么存结果集。不过要注意的是，return的时候，要保证async不要再往下执行了，即callback(err); process.nextTick(function() { async.auto({ findUserByUnPwFunc: function (callback) { var findUserByUnPwSql = “select * from user where username = '” + username + “’and password =’” + password + "’"; mysqldb.excute(findUserByUnPwSql, function (results) { callback(null, results); }); }, insertUserFunc: ['findUserByUnPwFunc’, function (callback, results) { var result = results.findUserByUnPwFunc; if (result.length > 0) { callback(“exist user cannot regist!”); return done(null, false, req.flash(‘signupMessage’, ‘该用户已存在！’)); } else { var insertUserSql = “insert into user(username,password) values('” + username + “’,’” + password + "’)"; mysqldb.excute(insertUserSql, function (results) { callback(null, true); }); } }], findUserByUnPwAfterFunc: ['findUserByUnPwFunc’, 'insertUserFunc’, function (callback, results) { console.log(results.insertUserFunc); var findUserByUnPwSql = “select * from user where username = '” + username + “’and password =’” + password + "’"; mysqldb.excute(findUserByUnPwSql, function (results) { callback(null, true); return done(null, results[0]); }); }] }); });