Query Builder: Table alias gets DB prefix when using subquery

Hello,

I have two similar queries. The difference is that the second one has an extra subquery in it.

The first query gets compiled nicely, in the second one, however, the table aliases in the main query get DB prefixes.

Looks like the extra subquery causes this weird problem, although it's not supposed to act on the main query.


Here's the first, correct query:

SELECT `m`.`id`, `group_id`, `name`, `label`, `pos`
    FROM `is_menu` `m`
        LEFT JOIN `is_menu_lang` `l` ON `l`.`id` = `m`.`id`
    WHERE `m`.`group_id` = '3' AND `inactive` = 0
    ORDER BY `pos`


Here's the second, messed up query, where "is_" is the DB prefix:

SELECT `is_m`.`id`, `group_id`, `name`, `label`, `pos`,
    (
        SELECT 1
        FROM `is_menu` `s`
        WHERE `s`.`group_id` = `m`.`id`
    ) `has_tree`
    FROM `is_menu` `m`
        LEFT JOIN `is_menu_lang` `l` ON `l`.`id` = `is_m`.`id`
    WHERE `is_m`.`group_id` = '4' AND `inactive` = 0
    ORDER BY `pos`


The way I built the query is probably not relevant, but here it is for the sake of completeness:

PHP Code:

if (!$table) $table = 'menu';

$select = 'm.id, group_id, name, label, pos';

$builder = $this->db
    ->table($table.' m')
    ->select($select);
 
if (!$more_levels_to_go) {
    $subquery = $this->db->table('menu s')
        ->select('1', false)
        ->where('s.group_id = m.id');
    $builder
        ->selectSubquery($subquery, 'has_tree');
}

$builder
    ->join($table.'_lang l', 'l.id = m.id', 'left')
    ->where('m.group_id', $id)
    ->where('inactive', 0)
    ->orderBy('pos'); 


Thanks.