openGauss每日一练第4天 | openGauss中一个数据库可以被多个用户访问

用户和角色有什么区别？
user 和 role的唯一区别是user是具有login用户属性的，而role默认不带logins属性，可以通过alter role方式添加，在其他方面二者没有区别。

一、学习目标

学习openGauss体系结构，使用多个用户访问同一个数据库

二、课程学习

创建user1、user2、user3用户，验证数据库musicdb可以被用户user1、user2、user3访问（分别在数据库中创建了一张表、插入数据、进行查询）。即一个数据库可以被多个用户访问。

三、课程作业

--测试环境准备
su - omm
gsql -r
--进入数据库omm，创建表空间、测试数据库
drop DATABASE  IF EXISTS  musicdb;
drop DATABASE  IF EXISTS  musicdb1;
drop DATABASE  IF EXISTS  musicdb2;
drop DATABASE  IF EXISTS  musicdb3;
drop tablespace IF EXISTS music_tbs;

CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE DATABASE musicdb  WITH TABLESPACE = music_tbs;

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实训环境示例：

root@modb:~# su - omm
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=# drop DATABASE  IF EXISTS  musicdb;
DROP DATABASE
omm=# drop DATABASE  IF EXISTS  musicdb1;
DROP DATABASE
omm=# drop DATABASE  IF EXISTS  musicdb2;
DROP DATABASE
omm=# drop DATABASE  IF EXISTS  musicdb3;
DROP DATABASE
omm=# drop tablespace IF EXISTS music_tbs;
DROP TABLESPACE
omm=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE DATABASE musicdb  WITH TABLESPACE = music_tbs;CREATE TABLESPACE
omm=# 
CREATE DATABASE
omm=# 

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1. 创建用户user1、user2、user3，授予user1、user2、user3数据库系统的SYSADMIN权限

--执行下面的SQL语句，创建用户user1、user2、user3：

 CREATE USER user1 IDENTIFIED BY 'kunpeng@1234';
 CREATE USER user2 IDENTIFIED BY 'kunpeng@1234';
 CREATE USER user3 IDENTIFIED BY 'kunpeng@1234';
 
--授予user1、user2、user3数据库系统的SYSADMIN权限：

ALTER USER user1 SYSADMIN;
ALTER USER user2 SYSADMIN;
ALTER USER user3 SYSADMIN;

--执行下面的命令，查看有哪些用户：
 \du
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omm=#  CREATE USER user1 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=#  CREATE USER user2 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=#  CREATE USER user3 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# 
omm=# ALTER USER user1 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user2 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user3 SYSADMIN;
ALTER ROLE
omm=# \du
                                                              List of roles
 Role name |                                                    Attributes                     
                               | Member of 
-----------+-----------------------------------------------------------------------------------
-------------------------------+-----------
 gaussdb   | Sysadmin                                                                          
                               | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Ope
 user2     | Sysadmin                                                                          
                               | {}
 user3     | Sysadmin                                                                          
                               | {}

ratoradmin, Policyadmin, UseFT | {}
 user1     | Sysadmin                                                                          
                               | {}
omm=# 

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2. 分别使用user1、user2、user3访问数据库musicdb2，创建各自的表，并插入数据。表名和数据如下：

表名分别为： products1、 products2、 products3

--以用户user1的身份在数据库musicdb2中创建表t1，并插入一条数据：
 \c musicdb2 user1
create table products1(product_id integer,product_name char(20),category char(30));
insert into products1(product_id,product_name,category) values(1502,'olympus camera','electrncs'),
(1601,'lamaze','toys'),
(1700,'wait interface','Books'),
(1666,'harry potter','toys');
 
--以用户user2的身份在数据库musicdb2中创建表t2，并插入一条数据：
  \c musicdb2 user2
create table products2(product_id integer,product_name char(20),category char(30));
insert into products2(product_id,product_name,category) values(1502,'olympus camera','electrncs'),
(1601,'lamaze','toys'),
(1700,'wait interface','Books'),
(1666,'harry potter','toys');


--以用户user3的身份在数据库musicdb2中创建表t3，并插入一条数据：
  \c musicdb2 user3
create table products3(product_id integer,product_name char(20),category char(30));
insert into products3(product_id,product_name,category) values(1502,'olympus camera','electrncs'),
(1601,'lamaze','toys'),
(1700,'wait interface','Books'),
(1666,'harry potter','toys');

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omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=#  \c musicdb2 user1
Password for user user1: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user1".
musicdb2=> create table products1(product_id integer,product_name char(20),category char(30));
CREATE TABLE
musicdb2=> insert into products1(product_id,product_name,category) values(1502,'olympus camera','electrncs'),
musicdb2-> (1601,'lamaze','toys'),
musicdb2-> (1700,'wait interface','Books'),
musicdb2-> (1666,'harry potter','toys');
INSERT 0 4
musicdb2=> \c musicdb2 user2
Password for user user2: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user2".
musicdb2=> create table products2(product_id integer,product_name char(20),category char(30));
CREATE TABLE
musicdb2=> insert into products2(product_id,product_name,category) values(1502,'olympus camera','electrncs'),
musicdb2-> (1601,'lamaze','toys'),
musicdb2-> (1700,'wait interface','Books'),
musicdb2-> (1666,'harry potter','toys');
INSERT 0 4
musicdb2=>   \c musicdb2 user3
Password for user user3: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user3".
musicdb2=> create table products3(product_id integer,product_name char(20),category char(30));
CREATE TABLE
musicdb2=> insert into products3(product_id,product_name,category) values(1502,'olympus camera','electrncs'),
musicdb2-> (1601,'lamaze','toys'),
musicdb2-> (1700,'wait interface','Books'),
musicdb2-> (1666,'harry potter','toys');
INSERT 0 4
musicdb2=> 

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3. 使用user1、user2、user3用户中的任何一个，查看当前数据库musicdb2有哪些表

omm=# \c musicdb2 user3
Password for user user3: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user3".
musicdb2=> \dt
                           List of relations
 Schema |   Name    | Type  | Owner |             Storage              
--------+-----------+-------+-------+----------------------------------
 public | products1 | table | user1 | {orientation=row,compression=no}
 public | products2 | table | user2 | {orientation=row,compression=no}
 public | products3 | table | user3 | {orientation=row,compression=no}
(3 rows)

musicdb2=> 

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