PHP & MySQL form question

Question

How do I allow all users to have their username field empty without having them need to enter a username when they submit the form using PHP and MySQL?

Here is part my PHP and MySQL code.

$username = mysqli_real_escape_string($mysqli, $purifier->purify(htmlentities(strip_tags($_POST['username']))));
if(isset($_POST['username'])) {
 // Make sure the username address is available:
 $u = "SELECT * 
 FROM users 
 WHERE username = '$username'
 AND user_id <> '$user_id'";
 $r = mysqli_query ($mysqli, $u) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($mysqli));
 if (mysqli_num_rows($r) == TRUE) { // Unavailable.
 echo '<p class="error">Your username is unavailable!</p>';
 $username = NULL;
 } else if(mysqli_num_rows($r) == 0) { // Available.
 $username = mysqli_real_escape_string($mysqli, $purifier->purify(htmlentities(strip_tags($_POST['username']))));
 }
}

• Ben S: possible duplicate of stackoverflow.com/questions/2650043/…
• SpikETidE: Please re-phrase the question.... What you are asking is not very clear...
• peakUC: its okay I solved it myself, thanks though.

Answer 1

This should do the trick: <input type="hidden" name="username" value="somevalue"/>.

Answer 2

if You did not want to fill your name in form then use hidden fied then use hidden field