来自PHP内部的SQL请求

I am trying to make a submit button that the user clicks after entering an email address. The email address should then be sent to a database. I am not sure why this is not working.

A database connection is established and tested beforehand. The file has a php extension. No error messages were received, but no data is uploaded to the database.

<form action='' method="post">
    <label>Email Address</label>

    <input type="text" name = "emailaddress" />

   <?php
     if ($_POST["emailaddress"] != "" && $_POST["emailaddress"] != null) {
       $youremail = $_POST["emailaddress"];
       mysql_query("INSERT INTO email_table (emailAddress) VALUES ('".$youremail."')");

       Print"Your information has been successfully added to the database.";
     }
   ?>

  <input type="submit" value="Add Email">

</form>