使用者對資料庫的許可權（登入、超級使用者許可權）

（1）檢視當前資料庫中有使用者highgo和使用者a

highgo=#\du

                             List of roles

 Role name |                   Attributes                   | Member of

-----------+------------------------------------------------+-----------

 a         |                                               | {}

 highgo   | Superuser, Create role, Create DB, Replication | {}

（2）檢視確認當前連線的使用者為超級使用者highgo，且該使用者後建立角色和資料庫的許可權等

highgo=#select current_user;

 current_user

--------------

 highgo

(1row)

（3）檢視當前叢集中的資料庫

highgo=#\l

                              List of databases

   Name   | Owner  | Encoding |  Collate  |   Ctype    | Access privileges

-----------+--------+----------+------------+------------+-------------------

 highgo   | highgo | UTF8     | zh_CN.utf8 |zh_CN.utf8 |

 template0 | highgo | UTF8     | zh_CN.utf8 | zh_CN.utf8 | =c/highgo        +

           |        |          |            |            | highgo=CTc/highgo

 template1 | highgo | UTF8     | zh_CN.utf8 | zh_CN.utf8 | =c/highgo        +

           |        |          |            |            | highgo=CTc/highgo

(3rows)

（4）使用普通使用者a連線資料庫正常

highgo=#\c highgo a

Youare now connected to database "highgo" as user "a".

highgo=>select current_user;

 current_user

--------------

 a

(1row)

（5）使用超級使用者highgo連線資料庫正常

highgo=>\c highgo highgo

Youare now connected to database "highgo" as user "highgo".

highgo=#select current_user;

 current_user

--------------

 highgo

(1row)

（6）在超級使用者連線highgo後，設定不允許普通使用者a連線資料庫

highgo=#alter role a nologin;

ALTER ROLE

highgo=#\c highgo a

致命錯誤:  不允許角色"a" 進行登入

Previousconnection kept

highgo=#

（7）在超級使用者連線highgo後，設定不允許普通使用者a連線資料庫後，賦予使用者a超級使用者許可權後仍然無法連線資料庫

highgo=#alter role a superuser;

ALTERROLE

highgo=#\du

                             List of roles

 Role name |                   Attributes                   | Member of

-----------+------------------------------------------------+-----------

 a        | Superuser, Cannot login                        | {}

 highgo   | Superuser, Create role, Create DB, Replication | {}

highgo=#\c highgo a

致命錯誤:  不允許角色"a" 進行登入

Previousconnection kept

（8）將登入資料庫的許可權賦予使用者a後，使用者a可登入資料庫

highgo=#alter role a login;

ALTERROLE

highgo=#\c highgo a

Youare now connected to database "highgo" as user "a".

highgo=#select current_user;

 current_user

--------------

 a