Sistema de registro em PHP - RockFire


<html>
<head>
<title>RockFire: Projetos</title>
</head>

<style type="text/css">

*
{
    text-decoration:none;
}

</style>

<body bgcolor=#151515>

<center>

<p>
<b><span style="color:grey">Registre-se no servidor</span></b><br><br>

<form action="">

<b><span style="color:#933">Nickname: </span><input type="text" name="username" maxlenght=20><br>
<b><span style="color:#933">Password: </span><input type="password" name="password" maxlenght=20></br>
<input type="submit" value="Registrar">
</b>

<br>

 </form>

</center>

</body>

</html>


<?php
    $connect = mysql_connect( "localhost" , "root" , "" );

    if( !$connect )
        die( "Conexão falhou: " . mysql_error() );

    $db = mysql_select_db( "registro" , $connect );

    if( $db )
    {
        $username = $_GET["username"];
        $password = $_GET["password"];

        if( strcmp( $username , "" ) && strcmp( $password , "" ) )
        {
            $exists = mysql_query( "SELECT * FROM `reg` WHERE `username` = '$username'" );

            if( mysql_num_rows( $exists ) )
            {
                echo "<center><span style=color:white>Está conta já existe !</span></center>";
            }
            else
            {
                mysql_query( "INSERT INTO `reg` VALUES('$username','$password',0)");
                echo "<center><span style=color:white>Parabéns você se registrou com sucesso</span></center>";
            }
        }
    }
?>