qb.php

<?php
// Trying to emulate
// SELECT l.*, MAX(s.sale_ts) FROM location AS `l` LEFT JOIN sales AS `s` ON l.id = s.location_id GROUP BY(s.location_id);
// But the group selects the last result.
$qb = $this->createQueryBuilder('l')
            ->leftJoin('l.sales', 's')
            ->where('l.is_active = 1')
            ->orderBy('l.id', 'ASC')
            ->addOrderBy('s.sale_ts', 'DESC')
            ->groupBy('l.id');