<?php

mysql_connect("localhost", "lee", "leecopter");
mysql_select_db("lee");

$username = mysql_real_escape_string($_POST['username']);

$check = mysql_query("SELECT username FROM users WHERE username='$username'");
$check_num_rows = mysql_num_rows($check);

if ($username==NULL)
	echo "Choose a username";

else if (strlen($username)<=3)
	echo "Username is too short";

else 
{
if ($check_num_rows==0)
	echo "Username is availible!";

else if ($check_num_rows==1)
	echo "Username has already been taken";
}
?>