/**
     * 查找所有子业务id(多级)
     * @param $id
     * @param $allIds
     */
    public static function getChildIds($id, &$allIds) {
        /** @var $query \Illuminate\Database\Eloquent\Builder */
        $query = self::where("parent_id", "=", $id);
        $rows = $query->get(['id', 'parent_id', 'name'])->all();
        foreach ($rows as $row) {
            $thisId = $row->getAttribute("id");
            /** @var $row Business */
            array_push($allIds, $thisId);
            self::getChildIds($thisId, $allIds);
        }
    }

    public static function getChildIdsNR($id) {
        $stack = array();
        $rows = self::where("parent_id", "=", $id)->get(['id', 'parent_id', 'name'])->all();
        if (!empty($rows)) {
            array_push($stack, $rows[0]);
        }
        $childIds = array();
        $i = 1;
        while (!empty($stack)) {
            $top = array_pop($stack);
            // 异常情况 上级id与这级id一样
            if ($top->id == $id) {
                break;
            }
            $children = self::where("parent_id", "=", $top->id)->get(['id', 'parent_id', 'name'])->all();
            array_push($childIds, $top->id);
            if (empty($children)) {
                if (isset($rows[$i])) {
                    array_push($stack, $rows[$i]);
                    $i += 1;
                }
            } else {
                foreach ($children as $child) {
                    array_push($stack, $child);
                }
            }
        }
        return $childIds;
    }

Usage:

// $businessIds = [];
// Business::getChildIds($this->businessId, $businessIds);
$businessIds = Business::getChildIdsNR($this->businessId);