mysql.query('SELECT xyu', function(err, res) {
    // Work with xyu...

   mysql.query('UPDATE xyu SET xyu WHERE xyu' , function (err, res) {
        // Work with other xyu error etc
   });
});


или

megaPromise = mysql.query('SELECT xyu');
megaPromise.then(function(data) {
    gigaPromise = mysql.query('UPDATE xyu SET xyu WHERE xyu');
    gigaPromise.then(function(data) {
        // Work with other xyu
    }).error(//some handler);
}).error(//some hanler)