public static function executeAddToWishlist($post_id, $sku, $serial, $advance = '') {
        global $wpdb;

        if (empty(self::getMemberId())) {
            return false;
        }

        $srow = self::getWishlistItemBySerial($serial);
        if (!empty($srow)) {
            // return `true` if the item already exists in wishlist
            return true;
        }

        $unit_price = null;
        $tempcart = new \usces_cart();

        /*
         * `get_realprice` uses `$this->serial` internally so we need to set `serial`
         * before calling it.
         *
         * We can't use `$usces->cart->get_realprice(...)` because spoofing `serial`
         * would directly affect the cart session.
         */
        $tempcart->serial = $serial;

        // `$sku` is automatically urldecoded in `get_realprice`
        $price = (int)$tempcart->get_realprice($post_id, $sku, 1, null, $unit_price);
        $res = $wpdb->insert(
            Master::getWishlistTableName(),
            [
                'mem_id' => self::getMemberId(),
                'quantity' => 1,
                'price' => $price,
                'advance' => $advance,
                'item_serial' => $serial,
            ],
            [
                '%d',
                '%d',
                '%d',
                '%s',
                '%s',
            ]
        );

        if ($res === false) {
            return false;
        }

        return true;
    }