Untitled

<?php
include("blog/dbinformation.php");
mysql_connect ($dbhost, $dbuser, $dbpass);
mysql_select_db ($dbname);
session_start();
if (!isset($_SESSION['loggedIn'])) {
    $_SESSION['loggedIn'] = false;
}
$num = 0;
if (isset($_POST['username'])) {
    $sql = mysql_query("SELECT * FROM users WHERE username='" . $_POST['username'] . "'");
    while($row = mysql_fetch_array($sql)){
        if (sha1($_POST['password']) == $row['password']) {
                $_SESSION['loggedIn'] = true;
        } else {
                die ('Incorrect.');
                $num ++;
        }
    }
}else{

    die ('Incorrect.');
    $num ++;

}
mysql_query("SELECT * FROM users WHERE username = '".$_POST['username']."' AND password = '".$_POST['password']."'");
if ($num .= 0){ ?>

<html><head><title>Login</title></head>
  <body>
    <p>You need to login</p>
    <form method="post">
      Username: <input type="password" name="username"> <br />
      Password: <input type="password" name="password"> <br />
      <input type="submit" name="submit" value="Login">
    </form>
  </body>
</html>

<?php
}
exit();
?>