mysql_ is deprecated! use mysqli_**
<?php
require_once 'connector.php';
$SQL = "SELECT u.username, h.score, h.date
FROM users AS u
JOIN highscores AS h ON (h.user_id = usersu.idusers_id)";
$result = mysql_query($SQL) or die( mysql_error() );
echo "<html>
<head>
<title>Highscores</title>
</head>
<body>";
if( mysql_num_rows($result) > 0 )
{
echo "<table border='1'>
<tr>
<th>user</th>
<th>score</th>
<th>Date</th>
</tr>";
while ( $row = mysql_fetch_array($result) )
{
echo "<tr>";
printf("<td>%s</td>", $row['username']);
printf("<td>%s</td>", $row['score']);
printf("<td>%s</td>", $row['date']);
echo "</tr>";
}
echo "</table>
</body>
</html>";
}
mysql_free_result($result);