获得SUM并导致多个JOIN表？

Question

我有这张桌子

订单

• orders_id
• order_article_id
• order_invoice_id
• order_customer_id
• order_qty

制品

• articles_id
• article_name
• article_qty
• article_price
• article_amount

客户

• customers_id
• customer_name
• customer_position
• customer_office

发票

• invoices_id
• 日期
• invoice_customer_id

和SQL Join Table

   $sql="SELECT customer_name, article_name, orders_id, article_price, order_qty, invoices_id FROM orders  LEFT JOIN articles ON order_article_id = articles_id
            LEFT JOIN invoices ON order_invoice_id = invoices_id 
            LEFT JOIN customers  on order_customer_id = customers_id";

从这个查询我需要得到的是这个结果示例

• 的 INVOICE_ID
• 的 CUSTOMER_NAME
• 该发票的AMOUNT = order_qty * article_price

是否可以在MySQL中执行此操作，或者我需要一些额外的PHP代码？

Answer 1

您需要一个聚合查询：

SELECT c.customer_name, i.invoices_id,
       sum(order_qty * a.article_price) as amount
FROM orders o LEFT JOIN
     articles a
     ON o.order_article_id = a.articles_id LEFT JOIN
     invoices i
     ON o.order_invoice_id = i.invoices_id LEFT JOIN
     customers c
     on o.order_customer_id = c.customers_id
GROUP BY c.customer_name, i.invoice_id;

请注意，我已添加表别名以更好地指定列的来源。这使查询更容易理解。