jQuery Validate issue with username checking with database

jQuery Validate issue with username checking with database

I got this code from the internet and it work perfectly for the email but with username there is a problem. When ever i type something it display the error 'Username have been taken' even with spam. I just wonder if anyone can fix it up. Thanks.

My Script

  2. $(document).ready(function () {
  3. $('.registerForm').validate({
  4.     onkeyup: false,
  5.     rules: {
  6.         username: {
  7.             required: true,
  8.             minlength: 5,
  9.             maxlength: 20,
  10.             remote: {
  11.             url: 'core/check2.php',
  12.         type: "post",
  13.         data: 
  14.         {
  15.           username: function() {
  16.             return $( "#username" ).val();
  17.             }
  18.             }
  19.             }
  20.         },
  21.         password: {
  22.             required: true,
  23.             minlength: 5,
  24.             maxlength: 20
  25.         },
  26.         confirmpassword: {
  27. required: true,
  28. minlength: 5,
  29. maxlength: 20,
  30. equalTo: password
  31.         },
  32.         email: {
  33.             required: true,
  34.             remote: {
  35.             url: 'core/check.php',
  36.         type: "post",
  37.         data: {
  38.           email: function() {
  39.             return $( "#email" ).val();
  40.             }
  41.             }
  42.             }
  43.         },
  44.         code: {
  45.             required: true,
  46.             remote: {
  47.             url: 'core/checkcode.php',
  48.         type: "post",
  49.         data: {
  50.           code: function() {
  51.             return $( "#code" ).val();
  52.             }
  53.             }
  54.             }
  55.         }
  56.     },
  57.     messages: {
  58.         username: {
  59.             required: "Enter a username.",
  60.             minlength: "Username too short",
  61.             maxlength: "Username too long",
  62.             remote: "Username have been taken"
  63.         },
  64.         password: {
  65.             required: "Enter a password.",
  66.             minlength: "Password too short",
  67.             maxlength: "Password too long",
  68.             remote: "Email have been taken"
  69.         },
  70.         confirmpassword: {
  71.             required: "Confirm your password.",
  72. minlength: "Password too short",
  73.             maxlength: "Password too long",
  74.             equalTo: "Your password does not match"
  75.         },
  76.         email: {
  77.             required: "Enter your email(NOT SPAM EMAIL).",
  78.             remote: "This Email have been taken"
  79.         },
  80.         code: {
  81.             required: "Enter your Register Code",
  82.             remote: "Invalid Code"
  83.         }
  84.     }

  86. });
  87. });






This is the php for username.
  1.  
  3. <?php
  4. include_once("db_connect.php");
  5. // USERNAME
  6. if(!empty($_POST['username'])) {
  7.     $username = $mysqli->real_escape_string($_POST['username']);
  8.     $query = "SELECT * FROM users WHERE username = '$username'";
  9.     $results = $mysqli->query($query);
  10.     if($results->num_rows == 0)
  11.     {
  12.         echo "true";  //good to register
  13.     }
  14.     else
  15.     {
  16.         echo "false"; //already registered
  17.     }
  18. } else {
  19.     echo "false";
  20. }
  21. ?>