所有人！我有三张table：订单、产品和产品。
我有这个功能：

public function getOrders($data = array()) {
        $sql = "SELECT MIN(o.date_added) AS date_start, MAX(o.date_added) AS date_end, COUNT(*) AS `orders`, SUM((SELECT SUM(op.quantity) FROM `" . DB_PREFIX . "order_product` op WHERE op.order_id = o.order_id GROUP BY op.order_id)) AS products, SUM((SELECT SUM(ot.value) FROM `" . DB_PREFIX . "order_total` ot WHERE ot.order_id = o.order_id AND ot.code = 'tax' GROUP BY ot.order_id)) AS tax, SUM((SELECT SUM(ot.value) FROM `" . DB_PREFIX . "order_total` ot WHERE ot.order_id = o.order_id AND ot.code = 'shipping' GROUP BY ot.order_id)) AS shipping_fee ,SUM(o.total) AS `total` FROM `" . DB_PREFIX . "order` o";

        if (!empty($data['filter_order_status_id'])) {
            $sql .= " WHERE o.order_status_id = '" . (int)$data['filter_order_status_id'] . "'";
        } else {
            $sql .= " WHERE o.order_status_id > '0'";
        }

        if (!empty($data['filter_date_start'])) {
            $sql .= " AND DATE(o.date_added) >= '" . $this->db->escape($data['filter_date_start']) . "'";
        }

        if (!empty($data['filter_date_end'])) {
            $sql .= " AND DATE(o.date_added) <= '" . $this->db->escape($data['filter_date_end']) . "'";
        }

        if (!empty($data['filter_group'])) {
            $group = $data['filter_group'];
        } else {
            $group = 'week';
        }

        switch($group) {
            case 'day';
                $sql .= " GROUP BY YEAR(o.date_added), MONTH(o.date_added), DAY(o.date_added)";
                break;
            default:
            case 'week':
                $sql .= " GROUP BY YEAR(o.date_added), WEEK(o.date_added)";
                break;
            case 'month':
                $sql .= " GROUP BY YEAR(o.date_added), MONTH(o.date_added)";
                break;
            case 'year':
                $sql .= " GROUP BY YEAR(o.date_added)";
                break;
        }

        $sql .= " ORDER BY o.date_added DESC";

        if (isset($data['start']) || isset($data['limit'])) {
            if ($data['start'] < 0) {
                $data['start'] = 0;
            }

            if ($data['limit'] < 1) {
                $data['limit'] = 20;
            }

            $sql .= " LIMIT " . (int)$data['start'] . "," . (int)$data['limit'];
        }

        $query = $this->db->query($sql);

        return $query->rows;
    }

我有一个报告页面，其中的结果按天/月或周分组，具体取决于开关值（如代码中所示）。
我需要的是添加一个自定义字段“rep”，它将对product表中“rep\u value”下的行的值求和。
我在产品表中有rep\ u值。
因此，最后的需要是在报告下面加上rep\u值的总和。我尝试了一些事情，但似乎是混乱的，代码没有返回正确的东西。
在我的尝试中，我在$sql查询中添加了以下代码：

SUM((SELECT 
    SUM(myma_product.rep_value)
FROM
    myma_product,
    myma_order_product
WHERE
    myma_product.product_id = myma_order_product.product_id)) as rep_values

但结果并不是我想要的，结果是不正确的。