Simple AJAX with JQuery

Simple AJAX with JQuery

<script type="text/javascript">
function register(){ //when the button is pressed, this function will be executed.
 $.ajax({
  type: "POST", // AJAX function
  url: "submit_data.php", //Method
  data:  "username=" + document.getElementById("username").value +
    "&email=" + document.getElementById("email").value, // executed when the button is pressed.
  success: function(html){
   $("#response").html(html); //response html output echo
  }
 });

 }
</script>

<form action="" method="post">
Simple AJAX with JQuery
  <p>
   <label for="name">Name:</label><br />
   <input type="text" name="username" id="name" size="25" />
  </p>
  <p>
   <label for="email">Email:</label><br />
   <input type="text" name="email" id="email" size="25" />
  </p>
  <p>
   <input type="button" name="submit" id="submit" value="Subscribe" onclick="register()"/> //
  </p>

</form>
<div id="response"></div> //The Response Div

submit_data.php
<?php
 $db_host = 'localhost';
      $db_user = 'user';
      $db_pass = 'pass';
      $db_name = 'db';
      $Username = $_POST['username'];
      $Email    = $_POST['email'];   
      // DB
      $connect = mysql_connect( $db_host, $db_user, $db_pass ) or die( mysql_error() );
      $connection = $connect;
      mysql_select_db( $db_name, $connect ) or die( mysql_error() );
      // Inserting into DB
      $qeuryInsert = mysql_query(" INSERT INTO `database` (`id`, `username`, `email`)
                                   VALUES ( ``, `$Username`, `$Email`)
                                ");
      if ($qeuryInsert){
          echo "You are now subscribed to our newsletter. Thank you!";
      } else {
          echo "Error!";
      }
 
  ?>