文档解释
ORA-28024: must revoke grants of external roles to this role/user
Cause: The user or role altered to IDENTIFIED GLOBALLY has external roles directly granted – these must be revoked, since external roles cannot be granted to global users or roles.
Action: Use REVOKE to revoke the external roles from the user or role to be ALTERed.
ORA-28024: 当一个角色/用户试图被授予被其他角色/用户授予的 外部角色时，将会抛出此错误。
官方解释
常见案例
一般处理方法及步骤
1）查询该用户授予了哪些外部角色。
SELECT * FROM dba_role_privs WHERE granted_role LIKE ‘%EXTERNAL%’ AND grantee = ‘用户名’;
2）撤掉这些外部角色授予
REVOKE 外部角色 FROM 用户名;
3）重试授予新角色
GRANT 角色 TO 用户名;
