已经在套接字IO中对握手进行排队后，不能使握手排队？

Question

cannot enqueue handshake after already enqueuing a handshake error found. Please solve my problem]. in SQL connection in Nodejs.

Here is my code :

 io.on('connection', function(socket) {
        con.connect(function(err) {
            socket.on('get_user_connect', function(data) {
                var sql = "select * from user";

                con.query(sql, function(err, result) {

                    if (err) {
                    console.log(err);
                    return;
                    }
                    io.sockets.emit('user_data', result);

                });
            });
        });
    });

  server.listen(8000, function() {
    console.log('listening on localhost:8000');
  });

Answer 1

You have SQL connection every time when Socket connect to server is. you have put SQL connect on Top and try it.

con.connect(function(err) {
    if (err) {
        console.log('Error connecting to Db' + err.stack);
        return;
    }
   // console.log('Connection established');
});

io.on('connection', function(socket) {

    socket.on('get_user_connect', function(data) {
        var sql = "select * from user";

        con.query(sql, function(err, result) {

            if (err) {
            console.log(err);
            return;
            }
            io.sockets.emit('user_data', result);

        });
    }); 
});