UPDATE fud28_read
SET user_id=2, last_view=1244710953,
      msg_id=(SELECT last_post_id FROM fud28_thread
                    WHERE id = fud28_read.thread_id)
WHERE user_id=2
     AND thread_id in (SELECT id FROM fud28_thread
                                WHERE forum_id=4 AND last_post_date > 0)

Index: users.inc.t
===================================================================
RCS file: /forum21/install/forum_data/src/users.inc.t,v
retrieving revision 1.171
diff -u -r1.171 users.inc.t
--- users.inc.t	3 May 2009 18:57:06 -0000	1.171
+++ users.inc.t	15 Jun 2009 17:12:27 -0000
@@ -781,7 +781,7 @@
 
 function user_mark_forum_read($id, $fid, $last_view)
 {
-	if (__dbtype__ == 'mysql') {
+	if (__dbtype__ == 'mysql' || __dbtype__ == 'sqlite') {
 		if ($GLOBALS['FUD_OPT_3'] & 1024) {
 			q('INSERT INTO {SQL_TABLE_PREFIX}read (user_id, thread_id, msg_id, last_view) SELECT '.$id.', id, last_post_id, '.__request_timestamp__.' FROM {SQL_TABLE_PREFIX}thread WHERE forum_id='.$fid.' AND last_post_date > '.$last_view.' ON DUPLICATE KEY UPDATE last_view=VALUES(last_view), msg_id=VALUES(msg_id)');
 		} else {