学习openGauss体系结构，使用一个用户访问多个数据库。
数据库用户user1可以访问不同的数据库（musicdb1、musicdb2、musicdb3）
实验中user1用户在数据库musicdb1中创建了表t11、
在数据库musicdb2创建了表t21
在数据库musicdb3中创建了表
课程作业
1.创建数据库musicdb10，创建用户user10，赋予sysadmin权限
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=# create tablespace music_tbs10 RELATIVE LOCATION 'tablespace/test_ts10';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb10 with tablespace=music_tbs10;
CREATE DATABASE
omm=# CREATE USER user10 IDENTIFIED BY 'kunpeng@1234';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# ALTER USER user10 sysadmin;
ALTER ROLE
2.用户user10访问数据库postgres，创建一个表并插入数据
omm=# \c postgres user10
Password for user user10:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "postgres" as user "user10".
openGauss=> create table zouyang(id int,name varchar(20));
CREATE TABLE
openGauss=> insert into zouyang values(1,'zouyang');
INSERT 0 1
openGauss=> select * from zouyang;
id | name
1 | zouyang
(1 row)
3.用户user10访问数据库omm，创建一个表并插入数据
openGauss=> \c omm user10
Password for user user10:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "omm" as user "user10".
omm=> create table yangkai2(id int,name varchar(20));
CREATE TABLE
omm=> insert into zouyang2 values(1,'zouyang');
INSERT 0 1
omm=> select * from zouyang2 ;
id | name
----+---------
1 | zouyang
(1 row)
4.用户user10访问数据库musicdb10，创建一个表并插入数据t31，验证了这个结论
omm=> \c musicdb10 user10
Password for user user10:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb10" as user "user10".
musicdb10=> create table zouyang3 (id int,name varchar(20));
CREATE TABLE
musicdb10=> insert into zouyang3 values(1,'zouyang');
INSERT 0 1
musicdb10=> select * from zouyang3 ;
id | name
----+---------
1 | zouyang
(1 row)
