YA: Login Checks 20130617184009AAPPF2Y

<?php
// Yahoo Answers' Question: http://answers.yahoo.com/question/index?qid=20130617184009AAPPF2Y
include('includes/functions.php');
session_start();

/***   Message Declaration   ***/
$message = '';


/***   Functions   ***/
function pv($name){
    $var = (isset( $_POST[$name] ))? trim( $_POST[$name] ) : '';
    return (@mysql_ping())? mysql_real_escape_string( $var ) : addslashes( $var );
}


if( isset( $_POST['login'] ) ){
    // Database Connection Needs to go Here.
    // Should at the least be MySQLi Functions
    // MySQL Functions are deprecated

    $username = pv('username');
    $password = pv('password');

    if( isset($username{0}) && isset($password{0})){
        // MD5 Hash Password.
        $password = md5($password);
        $stmt = "SELECT username FROM users WHERE username='{$username}' AND password='{$password}' LIMIT 1";
        $result = mysql_query($stmt);
        if( !$result ){
            $message .= 'Query Statement Error: ' . mysql_error() . '<br />' . PHP_EOL;
        }else if( mysql_num_rows($result) === 1){
            // Username and password are correct.
            $_SESSION['user'] = mysql_fetch_object($result)->username;
            header('Location: index.php');
            exit;
        }else{
            $message .= 'Username / Password Combo is incorrect. Please try again.<br />' . PHP_EOL;
        }
    }else{
        $message .= 'Username and Password are both required fields.<br />' . PHP_EOL;
    }

}

/***   Message Formatting   ***/
if( isset($message{1}) ){
    $message = '<div style="width: 500px;margin: auto;position: relative;border: 1px solid #999;">
        <h3 style="margin: 0;padding: 4px;background-color: #999;color: #fff;">Message</h3>
        <p style="padding: 8px;">' . $message . '</p>
    </div>';
}

include('login.php');
?>


also For HTML;


<?php
session_start(); // Has to be called before any output.
if( isset($_SESSION['user']) ){
    header('Location: index.php');
    exit;
}
?>
<html>
    <head>
        <title>Admin Area Login page</title>
    </head>
    <body>
        <?php if(isset($message)){ echo $message; } ?>
        <form action="dologin.php" method="POST">
            <table>
                <tr>
                    <td><span>Username:</span></td>
                    <td><input type="text" name="username" /></td>
                </tr>
                <tr>
                    <td><span>Password:</span></td>
                    <td><input type="password" name="password" /></td>
                </tr>
                <tr>
                    <td colspan="2" align="right"><input type="submit" name="login" value="Login" /></td>
                </tr>
            </table>
        </form>
    </body>
</html>