Jquery验证远程无法正常工作

Question

我的电子邮件检查程序的远程消息，如果数据库中可用或不可用，则无法正常运行。如果输入的电子邮件用户不可用则表示为false，则远程消息不会出现问题。

脚本：

<script>

  $(function() {


    $("form").validate({

        rules: {

            name: {
                required: true,
                minlength: 5
            },
            age: {
                required: true,
                minlength: 1
            },
            address: {
                minlength: 5,
                maxlength: 15,
                required: true
            },        
            gender: {
                required: true
            },
            email: {
                required: true,
                email: true,
                remote: {
                url: "check-email.php",
                type: "post"
            }
        }
        },

         messages: {
            email: {
                required: "Please enter your email.",
                email: "Please enter a valid email.",
                remote: "Email is already taken."
            }
        }
    });

  });

  </script>

签email.php

<?php
$host = "localhost";
$user = "root";
$pass = "";
$db = "test";

$dbc = new PDO("mysql:host=" . $host . ";dbname=" . $db, $user, $pass);
$dbc->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
header('Content-type: application/json');

    $requestedEmail  = @$_REQUEST['email'];

    $registeredEmail = "SELECT * FROM students WHERE email = :email ";

    $query = $dbc->prepare($registeredEmail);
    $query->bindParam(':email', $requestedEmail);
    $query->execute();
    $num_rows = $query->rowCount();  

    echo json_encode( ($num_rows === 0) ? 'true' : 'false' );


?>