SQL

Use Join On DataTables | Join Two Tables With ssp.class.php (Select & Search)

1-Replace table on server_processing.php File with your Join Query Like Bellow:
$table = <<<EOT
 (
    SELECT * FROM users INNER JOIN roles ON usr_role_id=roles.rol_id
 ) temp
EOT;
2-replace all instances of `$table` with $table to remove backticks.
3-Make sure all column names are unique otherwise use AS to assign an alias.

*There is also github.com/emran/ssp repository that contains enhanced ssp.class.php supporting JOINs.