sql-statement-set-default-role.md

title	summary
SET DEFAULT ROLE	TiDB 数据库中 SET DEFAULT ROLE 的使用概况。

SET DEFAULT ROLE

SET DEFAULT ROLE 语句默认设置将特定角色应用于用户。因此，用户不必执行 SET ROLE <rolename> 或 SET ROLE ALL 语句，也可以自动具有与角色相关联的权限。

语法图

SetDefaultRoleStmt:

SetDefaultRoleOpt:

RolenameList:

UsernameList:

示例

创建新角色 analyticsteam 和新用户 jennifer：

$ mysql -uroot

CREATE ROLE analyticsteam;
Query OK, 0 rows affected (0.02 sec)
GRANT SELECT ON test.* TO analyticsteam;
Query OK, 0 rows affected (0.02 sec)
CREATE USER jennifer;
Query OK, 0 rows affected (0.01 sec)
GRANT analyticsteam TO jennifer;
Query OK, 0 rows affected (0.01 sec)

需要注意的是，默认情况下，用户 jennifer 需要执行 SET ROLE analyticsteam 语句才能使用与角色相关联的权限：

$ mysql -ujennifer

SHOW GRANTS;
+---------------------------------------------+
| Grants for User                             |
+---------------------------------------------+
| GRANT USAGE ON *.* TO 'jennifer'@'%'        |
| GRANT 'analyticsteam'@'%' TO 'jennifer'@'%' |
+---------------------------------------------+
2 rows in set (0.00 sec)

SHOW TABLES in test;
ERROR 1044 (42000): Access denied for user 'jennifer'@'%' to database 'test'
SET ROLE analyticsteam;
Query OK, 0 rows affected (0.00 sec)

SHOW GRANTS;
+---------------------------------------------+
| Grants for User                             |
+---------------------------------------------+
| GRANT USAGE ON *.* TO 'jennifer'@'%'        |
| GRANT Select ON test.* TO 'jennifer'@'%'    |
| GRANT 'analyticsteam'@'%' TO 'jennifer'@'%' |
+---------------------------------------------+
3 rows in set (0.00 sec)

SHOW TABLES IN test;
+----------------+
| Tables_in_test |
+----------------+
| t1             |
+----------------+
1 row in set (0.00 sec)

执行 SET DEFAULT ROLE 语句将用户 jennifer 与某一角色相关联，这样该用户无需执行 SET ROLE 语句就能拥有与角色相关联的权限。

$ mysql -uroot

SET DEFAULT ROLE analyticsteam TO jennifer;
Query OK, 0 rows affected (0.02 sec)

$ mysql -ujennifer

SHOW GRANTS;
+---------------------------------------------+
| Grants for User                             |
+---------------------------------------------+
| GRANT USAGE ON *.* TO 'jennifer'@'%'        |
| GRANT Select ON test.* TO 'jennifer'@'%'    |
| GRANT 'analyticsteam'@'%' TO 'jennifer'@'%' |
+---------------------------------------------+
3 rows in set (0.00 sec)

SHOW TABLES IN test;
+----------------+
| Tables_in_test |
+----------------+
| t1             |
+----------------+
1 row in set (0.00 sec)

SET DEFAULT ROLE 语句不会自动将相关角色授予 (GRANT) 用户。若尝试为 jennifer 尚未被授予的角色执行 SET DEFAULT ROLE 语句会导致以下错误：

SET DEFAULT ROLE analyticsteam TO jennifer;
ERROR 3530 (HY000): `analyticsteam`@`%` is is not granted to jennifer@%

MySQL 兼容性

SET DEFAULT ROLE 语句与 MySQL 8.0 的角色功能完全兼容。如发现任何兼容性差异，请在 GitHub 上提交 issue。

另请参阅

• CREATE ROLE
• DROP ROLE
• GRANT <role>
• REVOKE <role>
• SET ROLE
• 基于角色的访问控制