MyBB Community Forums

I am currently working with a MyBB set up where I am trying to do an SQL query which can check if a user is part of a certain additional group. However, I am having difficulties.

MyBB stores additional group IDs in one VARCHAR field separated by commas, such as 1,23,27,30,49 etc. I know that in PHP I can explode strings using the comma as a delimiter. I understand that MySQL cannot explode, but I can use substring_index to achieve a similar goal. Point to note each user could have a random list of additional groups, so not all users would be the same, so the group 30 could be nth place depending on the user.

I am trying this 

$stmt = $conn->query('SELECT username, additionalgroups FROM my_users WHERE SUBSTRING_INDEX(30, ',', 1)');
foreach ($stmt as $row)
{
    print '<div class="name"><a href="#">' . $row['username'] . '</a></div>';
}

This does not seem to work though. Looking at https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_substring-index I seem to be following their way of constructing the condition, but I get the following error. I have somewhat been informed that my SQL does not provide a field in the SUBSTRING_INDEX either. 



Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: mode must be an integer in E:\xampp\htdocs\11thinfantrybrigade.co.uk\orbat.php:180 Stack trace: #0 E:\xampp\htdocs\11thinfantrybrigade.co.uk\orbat.php(180): PDO->query('SELECT username...', ', 1)') #1 {main} thrown in E:\xampp\htdocs\11thinfantrybrigade.co.uk\orbat.php on line 180



Any advice please? The end goal is to print a list of users that meet that criteria.


Thank you.

Edit: I know that there are some other threads on here with functions to achieve a similar thing, however, the page is sitting outside of the forum and just need to query the database.

Solved:
Help from Roemer on another forum helped with a solution:

$stmt = $conn->query('SELECT username FROM my_users WHERE CONCAT(",",additionalgroups,",") LIKE "%,30,%"');