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。
1.测试环境准备：
sql
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;
\set PROMPT1 '%n@%m %~%R%#'
CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE DATABASE musicdb WITH TABLESPACE = music_tbs;
2.创建用户 user1、user2、user3
--执行下面的SQL语句，创建用户user1、user2、user3：
sql
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：
sql
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：
sql
omm@local ~=#\du
List of roles
Role name | Attributes
| Member of
-----------+-----------------------------------------------------------------
-------------------------------------------------+-----------
gaussdb | Sysadmin
| {}
omm | Sysadmin, Create role, Create DB, Replication, Administer audit,
Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
user1 | Sysadmin
| {}
| {}
user2 | Sysadmin
| {}
user3 | Sysadmin 
3.在终端中，分别使用 user1、user2、user3 用户访问数据库 musicdb。
--以用户 user1 的身份在数据库 musicdb 中创建表 t1，并插入一条数据：
sql
\set PROMPT1 '%n@%m %~%R%#'
\c musicdb user1
create table t1(col1 char(20));
insert into t1 values('Hello kunpeng 1');
select * from t1;
--以用户 user2 的身份在数据库 musicdb 中创建表 t2，并插入一条数据：
sql
\set PROMPT1 '%n@%m %~%R%#'
\c musicdb user2
create table t2(col1 char(20));
insert into t2 values('Hello kunpeng 2');
select * from t2;
--以用户 user3 的身份在数据库 musicdb 中创建表 t3，并插入一条数据：
sql
\c musicdb user3
create table t3(col1 char(20));
insert into t3 values('Hello kunpeng 3');
select * from t3;
4.使用 user1、user2、user3 用户中的任何一个，执行如下命令，查看当前数据库 musicdb 有哪些表：
sql
user3@local musicdb=>\dt
List of relations
Schema | Name | Type | Owner | Storage
--------+------+-------+-------+----------------------------------
public | t1 | table | user1 | {orientation=row,compression=no}
public | t2 | table | user2 | {orientation=row,compression=no}
public | t3 | table | user3 | {orientation=row,compression=no}
(3 rows)
user3@local musicdb=>举例
1.创建用户 user01、user02、user03，授予 user01、user02、user03 数据库系统的 SYSADMIN 权限
sql
\set PROMPT1 '%n@%m %~%R%#'
\du
create user user01 identified by 'JiekeXu_1234';
create user user02 identified by 'JiekeXu_1234';
create user user03 identified by 'JiekeXu_1234';--授权
sql
alter user user01 SYSADMIN;
alter user user02 SYSADMIN;
alter user user03 SYSADMIN;
2.分别使用 user01、user02、user03 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 |
|---|---|
| product_id | INTEGER |
| product_name | Char(20) |
| category | Char(30) |
向表中插入数据：
sql
product_id product_name category
1502 olympus camera electrncs
1601 lamaze toys
1700 wait interface Books
1666 harry potter toys
create tablespace musicdb2_tbs relative location 'tablespace/musicdb2_tbs';
create database musicdb2 with tablespace = musicdb2_tbs;
\c musicdb2 user01
create table products1(product_id int,product_name Char(20), category Char(30));
insert into products1 values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
select * from products1;
\c musicdb2 user02
create table products2(product_id int,product_name Char(20), category Char(30));
insert into products2 values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
select * from products2;
\c musicdb2 user03
create table products3(product_id int,product_name Char(20), category Char(30));
insert into products3 values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
select * from products3;
sql
user03@local musicdb2=>select * from products1;
product_id | product_name | category
------------+----------------------+--------------------------------
1502 | olympus camera | electrncs
1601 | lamaze | toys
1700 | wait interface | Books
1666 | harry potter | toys
(4 rows)
user03@local musicdb2=>select * from products2;
product_id | product_name | category
------------+----------------------+--------------------------------
1502 | olympus camera | electrncs
1601 | lamaze | toys
1700 | wait interface | Books
1666 | harry potter | toys
(4 rows)
user03@local musicdb2=>select * from products3;
product_id | product_name | category
------------+----------------------+--------------------------------
1502 | olympus camera | electrncs
1601 | lamaze | toys
1700 | wait interface | Books
1666 | harry potter | toys
(4 rows)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
sql
user03@local musicdb2=>\dt
List of relations
Schema | Name | Type | Owner | Storage
--------+-----------+-------+--------+----------------------------------
public | products1 | table | user01 | {orientation=row,compression=no}
public | products2 | table | user02 | {orientation=row,compression=no}
public | products3 | table | user03 | {orientation=row,compression=no}
(3 rows)