如何计算发票的总价？

debugcn 发表于 Dev

马丁·阿杰

我有两个三个表：

// invoices
+----+----------------+
| id |  invoice_code  |
+----+----------------+
| 1  | d09823r230r4   |
| 2  | 34tf354f45tf   |
+----+----------------+

// commodities
+----+-------------+------------+--------+
| id | invoice_id  | product_id | number |
+----+-------------+------------+--------+
| 1  | 1           | 1          | 2      |
| 2  | 1           | 3          | 4      |
+----+-------------+------------+--------+
-- number columns is the number of each ordered product in the invoice

// products
// invoices
+----+-----------+---------+
| id |   name    |  price  |
+----+-----------+---------+
| 1  | SFX-300   | 15000   |
| 2  | GB32-b10  | 2000    |
| 3  | SVX-m30   | 1200    |
+----+-----------+---------+

我需要做的就是计算发票的总价。以下是计算发票总价的公式x：

$total_invoice_price = 0;
foreach( $invoice_x->commodities as $commodity){

    $total_invoice_price += ( $commodity.number * <products.price> )
}

echo $total_invoice_price;

问题是关于获取<products.price>. 它需要再加入一次products表。知道如何使用 Laravel 关系做到这一点吗？

菲利普

如果您只需要总价，这可以在纯 sql 中使用聚合语句和三个表的连接来完成。

SELECT invoice.invoice_code, SUM(product.price * commodities.number)
FROM invoice
JOIN commodities ON invoice.id = commodities.invoice_id
JOIN product ON product.id = commodities.product_id
GROUP BY invoice.id

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