How to print the Username of user with most posts

Question

I am working on my website (it's sort of a practice project) and I am trying to create a line on the home page that displays the User with the most posts on the Forums. The Forum is a MyBB forum, so everything is very easy to look at. I have the general idea of how to query information from SQL, and have even gotten the posts a few times, but getting the person with the most posts username has eluded me. Here is my current code:

<?php

mysql_connect("host", "username", "pass") or die(mysql_error());
mysql_select_db("db") or die(mysql_error());
echo "Top User: ", SELECT username FROM `mybb_users` ORDER BY `mybb_users`.`postnum` DESC LIMIT 0, 30 ;
echo "Users Posts: ", SELECT MAX(postnum) FROM  `mybb_users` or die(mysql_error());

?>

Now, I have been messing with this for an hour or so, I am a noob, so I have finally come here to ask of y'alls help. I used to have the "mysql_query" prefix in front of the queries but they're removed here as a last attempt. I'm trying to get it to be very simple and look like this:

Top User: John Doe

Posts: 2313

I like figuring things out for myself, and I see coding as a fun thing to do, but this is out of my league. I looked around but my feeble mind could not handle the other answers. I'm not sure what else to say other than thank you for your help!

Answer 1

Should be as simple as

 SELECT username, postnum FROM mybb_user ORDER BY postnum DESC LIMIT 1

or

SELECT username, count(username) as postCount FROM mybb_posts GROUP BY username ORDER BY postCount DESC limit 1

NOTE Do not use mysql* extension At very least use mysqli, but preferably PDO I am just showing it to you since that what you are using

    $result = mysql_query('SELECT username, postnum FROM mybb_user ORDER BY postnum DESC LIMIT 1');
    $row = mysql_fetch_assoc($result)
    echo $row['username'] . $row['postnum'];