将子查询添加到网格查询

Question

从this question 开始，我有另一个查询，我需要从数据中的所有负数中减去一个值 10。遗憾的是，我只是不确定如何实现与上一个问题中给出的相同的子查询。

有问题的查询是

SELECT 10 * (c.customer_x / 10), 10 * (c.customer_y / 10),
COUNT(*) as num_orders,
SUM(o.order_total)
FROM t_customer c 
JOIN t_order o
ON c.customer_id = o.customer_id
GROUP BY c.customer_x / 10, c.customer_y / 10
ORDER BY SUM(o.order_total) DESC;

计算每个方格的订单总数。

Answer 1

您的原始查询在下面的查询中没有太大变化。唯一的区别是新的连接和添加到SELECT 列表中的另一个术语：

SELECT 10 * (c.customer_x / 10) AS col1,
       10 * (c.customer_y / 10) AS col2,
       COUNT(*) AS num_orders,
       SUM(o.order_total) AS order_total_sum
FROM
(
    SELECT customer_id,
           CASE WHEN customer_x < 0 THEN customer_x - 10 ELSE customer_x END AS customer_x,
           CASE WHEN customer_y < 0 THEN customer_y - 10 ELSE customer_y END AS customer_y
    FROM t_customer
) c
INNER JOIN t_order o
    ON c.customer_id = o.customer_id
GROUP BY c.customer_x / 10,
         c.customer_y / 10
ORDER BY SUM(o.order_total) DESC

请注意，您可以在不使用我使用过的子查询的情况下解决这个问题。然而，子查询使它更具可读性，并让我们巧妙地计算调整后的customer_x 和customer_y 值。