MySQLi登录 - 没有错误但没有任何反应

Question

I'm almost sure that the following line is wrong:

if ($mQuery){

But since num_rows won't work, I'm using it.
If the condition is wrong, what should I change it for?

My PHP login code:

<?php
    $mysqli = mysqli_connect("localhost","myUser","myPass","myDB");
    $error = false;

    $mQuery = $mysqli->query('SELECT * FROM usuarios WHERE usuario = '.$mysqli->real_escape_string(md5($_POST['usuario'])).' AND  senha = '.$mysqli->real_escape_string(md5($_POST['senha'])));

    if ($mQuery){
        $mAjax = (isset($_SERVER['HTTP_X_REQUESTED_WITH']) and strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest');
        if ($mAjax)
        {
            header('Cache-Control: no-cache, must-revalidate');
            header('Expires: '.date('r', time()+(86400*365)));
            header('Content-type: application/json');

            echo json_encode(array(
            'logged' => !$error
            ));
            exit();
        }
        elseif (!$error)
        {
            exit();
        }
    }
?>

Answer 1

Try change your query from

$mQuery = $mysqli->query('SELECT * FROM usuarios WHERE usuario = '.$mysqli->real_escape_string(md5($_POST['usuario'])).' AND  senha = '.$mysqli->real_escape_string(md5($_POST['senha'])));

to

$mQuery = $mysqli->query("SELECT * FROM usuarios WHERE usuario = '" . 
          $mysqli->real_escape_string(md5($_POST['usuario'])) . 
          "' AND  senha = '" . 
          $mysqli->real_escape_string(md5($_POST['senha'])) . "'");