Display last row in database

How do I display the last value of the last row in a database?

mysql_select_db($database_conn_elements, $conn_elements);
$query_rs_forum_thread_messages = "SELECT * FROM forum_thread_messages WHERE forum_thread_id = " . $row_rs_forum_thread['id'];
$rs_forum_thread_messages = mysql_query($query_rs_forum_thread_messages, $conn_elements) or die(mysql_error());
$row_rs_forum_thread_messages = mysql_fetch_assoc($rs_forum_thread_messages);
$totalRows_rs_forum_thread_messages = mysql_num_rows($rs_forum_thread_messages);


i.e. when I print the below I only want to see the message column of the last row?

echo $row_rs_forum_thread_messages['message'];