You can use [get_current_user_id][1] to get the id of the user currently viewing the page, and [get_user_meta][2] to get the site_id associated with that user. For example:

```
<?php

$user_id = get_current_user_id();
$site_id = get_user_meta($user_id, 'site_id', true);
```

Note: This does assume there is a user logged in, you might get unexpected results if there isn't. So assuming you haven't already done so, make sure the page can only be viewed by a logged in user.

To then use this site_id to get the scores per 'site', you can use a [LEFT JOIN][3]. The query you can use is:

```
$result = $wpdb->get_result("SELECT `f_name`, `l_name`, IF(`tdata`.`score` = `tdata`.`maxscore`, 'PASSED', 'FAILED') as `score` FROM `c5k0o2h7gu_usermeta` `umeta` LEFT JOIN `wp_testing_data` `tdata` ON `tdata`.user_id = `umeta`.user_id WHERE `umeta`.meta_key = 'site_id' AND `umeta`.meta_value = '" . $site_id . "'");
```

Do note that this will give you a query result for every user that has a site_id associated that matches $site_id, even if there's no corresponding result in wp_testing_data. If you ONLY want those that have testing data, use INNER JOIN instead of LEFT JOIN.


  [1]: https://developer.wordpress.org/reference/functions/get_current_user_id/
  [2]: https://developer.wordpress.org/reference/functions/get_user_meta/
  [3]: https://www.mysqltutorial.org/mysql-left-join.aspx/