इसे यह करना चाहिए:
$result = mysql_query("SELECT * FROM notes WHERE note_author_id='$u_id' ORDER BY date_time DESC LIMIT 0, 10");
इसे यह करना चाहिए:
$result = mysql_query("SELECT * FROM notes WHERE note_author_id='$u_id' ORDER BY date_time DESC LIMIT 0, 10");