我编写了一个大型 MySQL 查询来检索给定用户的所有权限，最近发现由于 ONLY_FULL_GROUP_BY 模式，这在较新版本的 MySQL 中不起作用。

检索给定用户的所有授予权限的查询是:

SELECT
    `name`,
    `display_name`,
    `description`
FROM(
    SELECT * FROM (
        SELECT
            `p`.`id`,
            `p`.`name`,
            `p`.`display_name`,
            `p`.`description`,
            MAX(`r`.`priority`),
            IFNULL(`up`.`is_granted`, `rp`.`is_granted`) AS `is_granted`
        FROM `permissions` AS `p`
        LEFT JOIN `user_permissions` AS `up`
            ON `up`.`permission` = `p`.`id`
            AND `up`.`user` = 1
        LEFT JOIN `role_permissions` `rp`
            ON `rp`.`permission` = `p`.`id`
            AND `rp`.`role` IN(
                SELECT
                    `ur`.`role`
                FROM `user_roles` AS `ur`
                WHERE `ur`.`user` = 1
            )
        LEFT JOIN `roles` AS `r`
            ON `r`.`id` = `rp`.`role`
        GROUP BY `r`.`priority` DESC, `rp`.`permission`, `up`.`permission`
    ) AS `res`
    GROUP BY `res`.`id` ASC
) AS `res`
WHERE `res`.`is_granted` = 1

这会在启用了 ONLY_FULL_GROUP_BY 标志(默认启用)的较新 MySQL 安装上产生以下错误:SQL 错误 (1055):SELECT 列表的表达式 #5 不在 GROUP BY 子句中并且包含非聚合列'res.MAX(r.priority)' 在功能上不依赖于 GROUP BY 子句中的列；这与 sql_mode=only_full_group_by 不兼容。

我试图完全重写查询以提高效率并在启用标志的情况下工作，但是它并没有完全达到与第一个查询相同的目标。

SELECT
    u.id AS user_id,
    u.email AS user_email,
    up.permission AS user_permission_id,
    up.is_granted AS user_permission_is_granted,
    upp.name AS user_permission_name,
    upp.display_name AS user_permission_display_name,
    upp.description AS user_permission_description,
    ur.role AS role_id,
    urr.name AS role_name,
    urr.display_name AS role_display_name,
    urr.priority AS role_priority,
    urp.permission AS role_permission_id,
    urp.is_granted AS role_permission_is_granted,
    urpp.name AS role_permission_name,
    urpp.display_name AS role_permission_display_name,
    urpp.description AS role_permission_description
FROM users u
LEFT JOIN user_permissions up
    ON up.user = u.id
LEFT JOIN permissions upp
    ON upp.id = up.permission
LEFT JOIN user_roles ur
    ON ur.user = u.id
LEFT JOIN roles urr
    ON urr.id = ur.role
LEFT JOIN role_permissions urp
    ON urp.role = ur.role
LEFT JOIN permissions urpp
    ON urpp.id = urp.permission
WHERE u.id = 1

我应该怎么做？我已经尝试了几次，但无法真正找到在不禁用 ONLY_FULL_GROUP_BY 模式的情况下仅返回具有最高优先级的行的方法。

我应该只使用较新的查询并在应用程序代码中而不是在 SQL 查询中应用角色优先级吗？

Here is a DBFiddle with database structure and query.

根据上面 DBFiddle 的数据，我希望结果集如下所示:

| user_id | user_email        | permission_id | permission_name | permission_display_name | permission_description                             | is_granted |
| ------- | ----------------- | ------------- | --------------- | ----------------------- | -------------------------------------------------- | ---------- |
| 1       | user1@example.com | 1             | test1           | Test permission 1       | Role permission, should ONLY be granted to user 1  | 1          |
| 1       | user1@example.com | 2             | test2           | Test permission 2       | Role permission, should ONLY be granted to user 1  | 1          |
| 1       | user1@example.com | 3             | test3           | Test permission 3       | Role permission, should ONLY be granted to user 2  | 0          |
| 2       | user2@example.com | 3             | test3           | Test permission 3       | Role permission, should ONLY be granted to user 2  | 1          |
| 1       | user1@example.com | 4             | test4           | Test permission 4       | Role permission, should be granted to user 1 and 2 | 1          |
| 2       | user2@example.com | 4             | test4           | Test permission 4       | Role permission, should be granted to user 1 and 2 | 1          |
| 1       | user1@example.com | 5             | test5           | Test permission 5       | User permission, granted to user 1                 | 1          |
| 2       | user2@example.com | 6             | test6           | Test permission 6       | User permission, granted to user 2                 | 1          |

我希望权限 ID 3 返回 is_granted = 0 而不是不出现在结果集中的原因是因为用户最初被授予权限，但后来没有从角色 ID 2 授予它，哪个优先级高。

这个问题不是 SQL select only rows with max value on a column 的重复问题，因为它特别涉及我应该如何修改我的查询以解决 ONLY_FULL_GROUP_BY 模式。

最佳答案

通过仔细查看重复的问题并了解该问题的答案究竟是如何工作来解决的。

我必须创建一个 View ，将 role_permissions 表与 roles 表中的 priority 列连接在一起。然后我必须为每个用户获得所有最高优先级的角色权限。最后，我必须获得所有用户权限，这些权限不会覆盖用户的任何角色权限，并使用 UNION 将其与角色权限连接在一起。

这是我的解决方案:

SELECT
    u.id AS user_id,
    u.email AS user_email,
    p.id AS permission_id,
    p.name AS permission_name,
    p.display_name AS permission_display_name,
    p.description AS permission_description,
    IFNULL(up.is_granted, IFNULL(rp2.is_granted, rp1.is_granted)) AS is_granted
FROM users u
LEFT JOIN role_permissions_withpriority rp1
    ON rp1.role IN(SELECT role FROM user_roles WHERE user = u.id)
LEFT OUTER JOIN role_permissions_withpriority rp2
    ON rp2.role IN(SELECT role FROM user_roles WHERE user = u.id) AND rp2.permission = rp1.permission AND rp2.priority > rp1.priority
LEFT OUTER JOIN user_permissions up
    ON up.user = u.id AND up.permission = rp1.permission
LEFT JOIN permissions p
    ON p.id = rp1.permission
GROUP BY user_id, permission_id, is_granted
UNION
SELECT
    u.id AS user_id,
    u.email AS user_email,
    p.id AS permission_id,
    p.name AS permission_name,
    p.display_name AS permission_display_name,
    p.description AS permission_description,
    up.is_granted AS is_granted
FROM users u
LEFT JOIN user_permissions up
    ON up.user = u.id
LEFT JOIN permissions p
    ON p.id = up.permission
WHERE p.id IS NOT NULL
GROUP BY user_id, permission_id, is_granted

Here is an updated DBFiddle which demonstrates that the solution is working.

关于mysql - 获取给定用户的权限，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53806773/