作者：马顺华
从事运维管理工作多年，目前就职于某科技有限公司，熟悉运维自动化、OceanBase部署运维、MySQL 运维以及各种云平台技术和产品。并已获得OceanBase认证OBCA、OBCP证书。
第4天 | openGauss中一个数据库可以被多个用户访问
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
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。
1.测试环境准备：
1）–进入数据库omm
su - omm
gsql -r
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=#
2）–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;
omm=# drop DATABASE IF EXISTS musicdb;
NOTICE: database "musicdb" does not exist, skipping
omm=# DROP DATABASE
omm=# drop DATABASE IF EXISTS musicdb1;
NOTICE: database "musicdb1" does not exist, skipping
omm=# DROP DATABASE
omm=# drop DATABASE IF EXISTS musicdb2;
NOTICE: database "musicdb2" does not exist, skipping
DROP DATABASE
omm=#
omm=# drop DATABASE IF EXISTS musicdb3;
NOTICE: database "musicdb3" does not exist, skipping
DROP DATABASE
omm=# drop tablespace IF EXISTS music_tbs;
DROP TABLESPACE
omm=# NOTICE: Tablespace "music_tbs" does not exist, skipping.
3）–测试数据库
CREATE TABLESPACE music_tbs RELATIVE LOCATION ‘tablespace/test_ts1’;
CREATE DATABASE musicdb WITH TABLESPACE = music_tbs;
omm=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb WITH TABLESPACE = music_tbs;
CREATE DATABASE
omm=#
2、创建用户user1、user2、user3
1）–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’;
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=#
2）–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;
omm=# ALTER USER user1 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user2 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user3 SYSADMIN;
ALTER ROLE
omm=#
3）–执行下面的命令，查看有哪些用户：
\du
omm=# \du
List of roles
Role name | Attributes | Member o
f
-----------+------------------------------------------------------------------------------------------------------------------+---------
--
gaussdb | Sysadmin | {}
omm | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
user1 | Sysadmin | {}
user2 | Sysadmin | {}
user3 | Sysadmin | {}
omm=#
3、在终端中，分别使用user1、user2、user3用户访问数据库musicdb。
1）–以用户user1的身份在数据库musicdb中创建表t1，并插入一条数据：
\c musicdb user1
create table t1(col1 char(20));
insert into t1 values(‘Hello kunpeng 1’);
select * from t1;
omm=# \c musicdb user1
Password for user user1:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user1".
musicdb=> create table t1(col1 char(20));
CREATE TABLE
musicdb=> insert into t1 values('Hello kunpeng 1');
INSERT 0 1
musicdb=> select * from t1;
col1
----------------------
Hello kunpeng 1
(1 row)
2）–以用户user2的身份在数据库musicdb中创建表t2，并插入一条数据：
\c musicdb user2
create table t2(col1 char(20));
insert into t2 values(‘Hello kunpeng 2’);
select * from t2;
musicdb=> \c musicdb user2
Password for user user2:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user2".
musicdb=> create table t2(col1 char(20));
CREATE TABLE
musicdb=> insert into t2 values('Hello kunpeng 2');
INSERT 0 1
musicdb=> select * from t2;
(1 row)
musicdb=> col1
----------------------
Hello kunpeng 2
musicdb=>
3）–以用户user3的身份在数据库musicdb中创建表t3，并插入一条数据：
\c musicdb user3
create table t3(col1 char(20));
insert into t3 values(‘Hello kunpeng 3’);
select * from t3;
musicdb=> \c musicdb user3
Password for user user3:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user3".
musicdb=> create table t3(col1 char(20));
CREATE TABLE
musicdb=> insert into t3 values('Hello kunpeng 3');
INSERT 0 1
musicdb=> select * from t3;
col1
----------------------
Hello kunpeng 3
(1 row)
musicdb=>
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：
\dt
musicdb=> \c musicdb user1
Password for user user1:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user1".
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)
musicdb=> \c musicdb user2
Password for user user2:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "user2".
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)
课程总结
1.创建用户user1、user2、user3，授予user1、user2、user3数据库系统的SYSADMIN权限
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
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
