mysql 使 group by 函数符合 only_full_group_by

Question

我在这里找到了很多关于 only_full_group_by 的信息，当您收到 #1055 错误时，它处于严格模式。我发现的解决方案都涉及禁用用户警告可能导致其他问题的严格模式。我的问题是关于使查询符合而不是变通。谁能告诉我在严格模式下是否可以投诉以下查询，如果可以，会有什么变化？

错误 - #1055 - 选择列表的表达式 #2 不在 group by 子句中，并且包含在功能上不依赖于 GROUP BY 子句中的列的非聚合列 xxx；这与 sql_mode=only_full_group_by 不兼容

 SELECT 
            post_id,
            name,
            Email,
            CustomerId,
            DeliveryDate,
            DeliveryTime,
            DeliveryType,
            Zip,
            OrderNote,
            PaymentTotal,
            OrderStatus
    
        FROM
            (SELECT 
                post_id,
                    name,
                    MAX((CASE WHEN (meta_key = '_rpress_payment_user_email') THEN meta_value END)) AS `Email`,
                    MAX((CASE WHEN (meta_key = '_rpress_payment_customer_id') THEN meta_value END)) AS `CustomerId`,
                    MAX((CASE WHEN (meta_key = '_rpress_delivery_date') THEN meta_value END)) AS `DeliveryDate`,
                    MAX((CASE WHEN (meta_key = '_rpress_delivery_time') THEN meta_value END)) AS `DeliveryTime`,
                    MAX((CASE WHEN (meta_key = '_rpress_delivery_type') THEN meta_value END)) AS `DeliveryType`,
                    MAX((CASE WHEN (meta_key = '_rpress_delivery_zip') THEN meta_value END)) AS `Zip`,
                    MAX((CASE WHEN (meta_key = '_rpress_order_note') THEN meta_value END)) AS `OrderNote`,
                    MAX((CASE WHEN (meta_key = '_rpress_payment_total') THEN meta_value END)) AS `PaymentTotal`,
                    MAX((CASE WHEN (meta_key = '_order_status') THEN meta_value END)) AS `OrderStatus`
            FROM
                (`wp_postmeta` `t1`
            JOIN `wp_rpress_customers` `t2` ON ((0 <> FIND_IN_SET(`t1`.`post_id`, `t2`.`payment_ids`))))
            GROUP BY `t1`.`post_id` , `t2`.`name`) `derived_table`

Answer 1

您的代码看起来像是一个有效的聚合查询。但是，它可以大大简化：不需要谓词周围的大多数括号，并且不需要嵌套聚合查询。我还建议使用有意义的表别名，并在查询中的所有列前面加上它们所属的表（别名）。

所以：

SELECT 
    pm.post_id,
    c.name,
    MAX(CASE WHEN pm.meta_key = '_rpress_payment_user_email'  THEN pm.meta_value END) AS Email,
    MAX(CASE WHEN pm.meta_key = '_rpress_payment_customer_id' THEN pm.meta_value END) AS CustomerId,
    MAX(CASE WHEN pm.meta_key = '_rpress_delivery_date'       THEN pm.meta_value END) AS DeliveryDate,
    MAX(CASE WHEN pm.meta_key = '_rpress_delivery_time'       THEN pm.meta_value END) AS DeliveryTime,
    MAX(CASE WHEN pm.meta_key = '_rpress_delivery_type'       THEN pm.meta_value END) AS DeliveryType,
    MAX(CASE WHEN pm.meta_key = '_rpress_delivery_zip'        THEN pm.meta_value END) AS Zip,
    MAX(CASE WHEN pm.meta_key = '_rpress_order_note'          THEN pm.meta_value END) AS OrderNote,
    MAX(CASE WHEN pm.meta_key = '_rpress_payment_total'       THEN pm.meta_value END) AS PaymentTotal,
    MAX(CASE WHEN pm.meta_key = '_order_status'               THEN pm.meta_value END) AS OrderStatus
FROM wp_postmeta pm
INNER JOIN wp_rpress_customers c ON FIND_IN_SET(pm.post_id, c.payment_ids)
GROUP BY pm.post_id, c.name

我还删除了标识符周围的反引号，这似乎不是很有帮助（如果需要，您可以恢复该更改）。