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;
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=#
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
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=#
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
| 字段名 | 数据类型 | 含义 |
|---|---|---|
| product_id | INTEGER | 产品编号 |
| product_name | Char(20) | 产品名 |
| category | Char(30) | 种类 |
| 向表中插入数据： | ||
| product_id | product_name | category |
| - | - | - |
| 1502 | olympus camera | electrncs |
| 1601 | lamaze | toys |
| 1700 | wait interface | Books |
| 1666 | harry potter | toys |
--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');
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=>
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=>