MySQL 这与 sql_mode=only_full_group_by 不兼容

Question

SELECT u.*, p.name as plan, COUNT(m.user_id) as totalprojects
FROM users u 
LEFT JOIN plans p ON p.id = u.access
LEFT JOIN members m ON m.user_id = u.id
WHERE u.email = 'email address';

所以我有上面的内容，并且我在 Mac 上运行 MySQL 并尝试执行

set global sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION, ONLY_FULL_GROUP_BY';

这说的是

Query OK, 0 rows affected (0.00 sec)

SELECT @@sql_mode

显示

+------------------------------------------------------------------------------------------------------------------------+
| @@sql_mode                                                                                                             |
+------------------------------------------------------------------------------------------------------------------------+
| STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

Answer 1

是的。上述查询与 sql_mode=only_full_group_by 不兼容。如果启用了 only_full_group_by，则必须提及在 GROUP BY 子句中选择的所有列。这里没有任何 GROUP BY 子句，并且也使用聚合函数 (COUNT)。理想情况下，如果启用了 only_full_group_by，则此查询应该失败。默认情况下，从 MySQL 5.7 开始启用此功能。

请引用https://dev.mysql.com/doc/refman/5.7/en/group-by-handling.html了解详情