1.创建用户user1、user2和user3，user1具有CREATEROLE权限，user2具有CREATEDB权限，要求使用两种不同的方法设置密码
omm=# create user user1 password 'yangkai_123';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# create user user2 identified by 'yangkai_123';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# create user user3 identified by 'yangkai_123';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# alter user user1 CREATEROLE;
ALTER ROLE
omm=# alter user user2 createdb;
ALTER ROLE
2.修改用户user1的密码
omm=# alter user user1 identified by 'yangkai_9999' replace 'yangkai_123';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
ALTER ROLE
3.重命名用户user2
omm=# alter user user2 rename to yangbaji9999;
4.将用户user1的权限授权给用户user3，再回收用户user3的权限
grant user1 to user3;
omm=# \du user1;
List of roles
Role name | Attributes | Member of
-----------+-------------+-----------
user1 | Create role | {}
omm=# \du yangbaji9999
List of roles
Role name | Attributes | Member of
--------------+------------+-----------
yangbaji9999 | Create DB | {}
omm=# \du user3;
List of roles
Role name | Attributes | Member of
-----------+------------+-----------
user3 | | {user1}
omm=# revoke user1 from user3;
REVOKE ROLE
omm=# \du user3;
user3 | | {}
omm=# List of roles
Role name | Attributes | Member of
omm=# \du+
List of roles
Role name | Attributes | Member of | Description
omm=# --------------+------------------------------------------------------------------------------------------------------------------+-----------+-------------
gaussdb | Sysadmin | {} |
omm | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {} |
user1 | Create role | {} |
user3 | | {} |
yangbaji9999 | Create DB | {} |
yangkai
5.删除所有创建用户
omm=# drop user user1;
DROP ROLE
omm=# drop user yangbaji9999;
DROP ROLE
omm=# drop user user3;
DROP ROLE
