先通过最新的对话订购MySQL收件箱？

I've a MySQL/PHP code for a private messaging system that I built. It works great although I'm fairly new to it all so struggling to get the message threads to display by newest first. Is there any chance you could offer advice? The current code is as follows:

$result = '';

$nowTime = time();

$getmessages = mysql_query("SELECT * FROM messages WHERE msg_to = '$session_memberid' GROUP BY msg_from ORDER BY ID DESC");
while($iamessages = mysql_fetch_array($getmessages))
{
$msg_id = $iamessages['ID'];
$msg_from = $iamessages['msg_from'];
$msg_conversation = $iamessages['conversation'];



$getmsgdata = mysql_query("SELECT * FROM messages WHERE msg_to = '$session_memberid' AND msg_from = '$msg_from' ORDER BY ID DESC LIMIT 1");
while($imsd = mysql_fetch_array($getmsgdata))
{
$msg_message = $imsd['msg_message'];
$msg_time = $imsd['time'];
$msg_read = $imsd['msg_read'];
}

$msg_conversation = suitcrypt($msg_conversation);

if ( $msg_read == 'no' ) { $msgclass = "messagepostunread"; } else { $msgclass = "messagepost"; }

$getfromdata = mysql_query("SELECT FullName, Username, status FROM members WHERE ID = '$msg_from'");
while($ifd = mysql_fetch_array($getfromdata))
{
$msg_from_name = $ifd['FullName'];
$msg_from_username = $ifd['Username'];
$msg_from_status = $ifd['status'];
}

$getfromdata1 = mysql_query("SELECT Link FROM images WHERE MemberID = '$msg_from' AND is_primary = 'yes'");
while($ifd1 = mysql_fetch_array($getfromdata1)) {
$msg_from_img = $ifd1['Link'];
}

$timepass = timing($msg_time);
if ( $timepass == 'data' ) {
$timepass = date("dS M", $msg_time);
}

if ( ( $msg_from_status == 'full' ) || ( $msg_from_status == 'active' ) ) {

$result .= "
        <div class=\"$msgclass\" onclick=\"showconversation('$msg_conversation');\">
        <img src=\"m/members_image/$msg_from/thumb-$msg_from_img\" class=\"feedpic\" width=\"55\" height=\"55\" /><div class=\"messageposttext\"><a href=\"/$msg_from_username\">$msg_from_name</a>:<div class=\"inboxfeedreply\">Reply &nbsp; &middot; &nbsp; $timepass</div><br />$msg_message</div>
        </div>
        <div class=\"splittermessages\"></div>
";
}

Within each table entry in the messages table there is a 'time' stamp. Here's an example of the time entries: 1367680391. What's the best way to order the threads by newest reply first?

First off I think you should group by $msg_conversation and find the last date on each conversation. With the code below you have the conversatons ordered by the last message each conversation/thread had.

$result = '';

$nowTime = time();

$getmessages = mysql_query("SELECT conversation, max(date) FROM messages WHERE msg_to = '$session_memberid' GROUP BY conversation ORDER BY max(date)");
while($iamessages = mysql_fetch_array($getmessages))
{
$msg_conversation = $iamessages['conversation'];
...

Further on you can get the messages for each conversation by date descending.

I got someone to help and the answer was to update the query to the following:

$getmessages = mysql_query("SELECT * FROM messages WHERE msg_to = '$session_memberid' GROUP BY msg_from ORDER BY MAX(time) DESC");