Question

假设我有三个表，客户，订单和订单详细信息。

我这样做：

SELECT orders.ordersId, sum(orderDetails.total)
FROM orders
LEFT OUTER JOIN orderDetails ON orders.ordersId = orderDetails.ordersId 
GROUP BY orders.ordersId

但是我们可以说订单表包含customersId。如何加入customers表，以便我还可以将客户的名称添加到所选字段中？

谢谢，

百里

Answer 1

SELECT orders.ordersId, sum(orderDetails.total), customer.name
FROM orders
LEFT OUTER JOIN orderDetails ON orders.ordersId = orderDetails.ordersId
LEFT OUTER JOIN customer on customer.customerid = orders.customerid 
GROUP BY orders.ordersId , customer.name

尝试一下或类似的东西。

Answer 2

您可以这样做，如果需要，您可以获得超过客户名称的信息：

SELECT o.ordersId, o.orderTotal, c.customername, c.(other customer data)
FROM 
(
    SELECT orders.ordersId
            , sum(orderDetails.total) as orderTotal
            , orders.customersid
    FROM orders
    LEFT OUTER JOIN orderDetails 
            ON orders.ordersId = orderDetails.ordersId 
    GROUP BY orders.ordersId, orders.customersid
) o
LEFT JOIN customers c
    ON o.customersid = c.customersid

加入一个小组

2 个答案: