SQL LEFT JOIN子查询别名

小编典典

SQL LEFT JOIN子查询别名

sql

我正在运行此SQL查询：

SELECT wp_woocommerce_order_items.order_id As No_Commande
FROM  wp_woocommerce_order_items
LEFT JOIN 
    (
        SELECT meta_value As Prenom
        FROM wp_postmeta
        WHERE meta_key = '_shipping_first_name'
    ) AS a
ON wp_woocommerce_order_items.order_id = a.post_id
WHERE  wp_woocommerce_order_items.order_id =2198

我得到这个错误：

＃1054-‘on子句’中的未知列’a.post_id’。

我认为我的代码非常简单，但是我做错了。我究竟做错了什么？

阅读 268

2021-03-17

共1个答案

小编典典

您没有post_id在子查询中选择。您必须像下面这样在子查询中选择它：

SELECT wp_woocommerce_order_items.order_id As No_Commande
FROM  wp_woocommerce_order_items
LEFT JOIN 
    (
        SELECT meta_value As Prenom, post_id  -- <----- this
        FROM wp_postmeta
        WHERE meta_key = '_shipping_first_name'
    ) AS a
ON wp_woocommerce_order_items.order_id = a.post_id
WHERE  wp_woocommerce_order_items.order_id =2198

2021-03-17