<?php

/*
* Used to modify a user's default group in MyBB
* @param string $username
* @param int $gid
*/

function setUserGroup($username, $gid)
{
    $mysqli = new mysqli("localhost", "username", "password", "database");
    $query = $mysqli->prepare("SELECT * FROM mybb_users WHERE username=?");
    $query->bind_param("s", $username);
    $query->execute();
    $query->store_result();
    $count = $query->num_rows;
    $query->close();

    if($count == 0)
    {
        echo "Username is incorrect !";
    }
    else
    {
        $gid = (int) $gid;

        $query = $mysqli->prepare("SELECT title FROM mybb_usergroups WHERE gid=?");
        $query->bind_param("i", $gid);
        $query->bind_result($gtitle);
        $query->execute();
        $query->store_result();
        $count = $query->num_rows;
        $query->fetch();
        $query->close();

        if($count == 0)
        {
            echo "Group ID is incorrect !";
        }
        else
        {
            $query = $mysqli->prepare("UPDATE mybb_users SET usergroup=? WHERE username=?");
            $query->bind_param("is", $gid, $username);
            $query->execute();
            $query->close();

            echo "$username's group has been changed to $gtitle (gid: $gid)";
        }
    }
}

//Usage : setUserGroup("username", 1);

?>