AJAX Username Availability checking

Put this javascript within your "Head" tag.


the form control should like this,

call the CheckUsername() function inside the username control in onchange event,
onChange='CheckUsername(this.value);'
create one "div" tag put inside that tag
id='usernameresult'

create one check.php file, it should consists,

mysql_connect("localhost","root","1234");
mysql_select_db("database_name");

if(isset($_GET['username'])){ // ElseIf they are want to check their username.

$user=stripslashes(strip_tags(htmlspecialchars($_GET['username'], ENT_QUOTES))); // Cleans all nasty input from the username.
$check=mysql_num_rows(mysql_query("SELECT * FROM `registration` WHERE `Usern` = '".$user."'")); // Checks to see if a user is in the `users` table or not.

if($check == 0){ // If there is no username in the database that matches the input one.
echo ''.$user.' is Available!'; // Yay we can use it.
}elseif($check != 0){ // ElseIf there is a username in the database.
echo ''.$user.' is Not Available!'; // None for you higgans.
} // End If.