Question

自从我编写了复杂的SQL语句以来，已经很久了。我正在WordPress / WooCommerce中工作，试图对每个客户进行订单汇总。

当我开始使用此SQL语句进行测试时，只要获得包含客户信息的订单列表，它就可以工作：

SELECT wp_users.ID as userID,
       wp_posts.post_date,
       wp_posts.post_type,
       wp_users.user_email,
       MAX(CASE WHEN wp_usermeta.meta_key = 'billing_first_name' THEN wp_usermeta.meta_value END) as firstName,
       MAX(CASE WHEN wp_usermeta.meta_key = 'billing_last_name' THEN wp_usermeta.meta_value END) as lastName,
       MAX(CASE WHEN wp_woocommerce_order_itemmeta.meta_key = '_line_total' THEN wp_woocommerce_order_itemmeta.meta_value END) as orderTotal

FROM wp_posts
  INNER JOIN wp_postmeta
     ON wp_postmeta.post_id = wp_posts.ID
  INNER JOIN wp_users
     ON wp_postmeta.meta_key = '_customer_user'
     AND wp_users.ID = wp_postmeta.meta_value
  INNER JOIN wp_usermeta
     ON wp_usermeta.user_id = wp_users.ID
  INNER JOIN wp_woocommerce_order_items
     ON wp_woocommerce_order_items.order_id = wp_posts.ID
  INNER JOIN wp_woocommerce_order_itemmeta
     ON wp_woocommerce_order_itemmeta.order_item_id = wp_woocommerce_order_items.order_item_id
WHERE wp_posts.post_type IN ('shop_order','shop_subscription') 
GROUP BY wp_posts.ID

结果显示在此处的第一张图片中：https://imgur.com/a/mZs9Iej

如果我将这些结果汇总到excel中（到目前为止只有1个测试用户），则该用户的总费用为$ 4281。

如果我然后尝试对每个用户在SQL语句中进行SUM运算，例如此处（仅更改了两行，最后一个MAX更改为SUM，GROUP BY更改为wp_users.ID）：

SELECT wp_users.ID as userID,
       wp_posts.post_date,
       wp_posts.post_type,
       wp_users.user_email,
       MAX(CASE WHEN wp_usermeta.meta_key = 'billing_first_name' THEN wp_usermeta.meta_value END) as firstName,
       MAX(CASE WHEN wp_usermeta.meta_key = 'billing_last_name' THEN wp_usermeta.meta_value END) as lastName,
       SUM(CASE WHEN wp_woocommerce_order_itemmeta.meta_key = '_line_total' THEN wp_woocommerce_order_itemmeta.meta_value END) as userTotal

FROM wp_posts
  INNER JOIN wp_postmeta
     ON wp_postmeta.post_id = wp_posts.ID
  INNER JOIN wp_users
     ON wp_postmeta.meta_key = '_customer_user'
     AND wp_users.ID = wp_postmeta.meta_value
  INNER JOIN wp_usermeta
     ON wp_usermeta.user_id = wp_users.ID
  INNER JOIN wp_woocommerce_order_items
     ON wp_woocommerce_order_items.order_id = wp_posts.ID
  INNER JOIN wp_woocommerce_order_itemmeta
     ON wp_woocommerce_order_itemmeta.order_item_id = wp_woocommerce_order_items.order_item_id
WHERE wp_posts.post_type IN ('shop_order','shop_subscription') 
GROUP BY wp_users.ID

它返回的总和为$ 340k，而不是$ 4k，太大，如下图所示：https://imgur.com/a/mZs9Iej

有人可以发现我犯的错误吗？任何帮助表示赞赏！

Answer 1

尝试一下

SELECT users.ID as userID,
       posts.post_date,
       posts.post_type,
       users.user_email,
       fname.meta_value as firstName,
       lname.meta_value as lastName,
       SUM(itemmeta.meta_value) as userTotal
FROM wp_posts posts
  INNER JOIN wp_postmeta postmeta
     ON postmeta.post_id = posts.ID
     AND postmeta.meta_key = '_customer_user'
  INNER JOIN wp_users users
     ON users.ID = postmeta.meta_value
  INNER JOIN wp_woocommerce_order_items items
     ON items.order_id = posts.ID
  INNER JOIN wp_woocommerce_order_itemmeta itemmeta
     ON itemmeta.order_item_id = items.order_item_id
     AND itemmeta.meta_key = '_line_total'
  LEFT JOIN wp_usermeta fname
     ON fname.user_id = users.ID 
     AND fname.meta_key = 'billing_first_name'
  LEFT JOIN wp_usermeta lname
     ON lname.user_id = users.ID 
     AND lname.meta_key = 'billing_last_name'
WHERE posts.post_type IN ('shop_order','shop_subscription') 
GROUP BY users.ID

我为表引入了别名，并用左联接替换了您的case构造。

似乎您需要指定meta_keys作为条件，因为否则您将联接与meta_key不匹配的行。反过来，这会将wp_woocommerce_order_itemmeta中的联接行相乘，因此也就是您要总结的属性。

SQL：汇总CASE语句返回错误结果

1 个答案: