学习目标

学习openGauss体系结构，使用一个用户访问多个数据库。

课程学习

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t31，验证了这个结论。

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=# \l
                         List of databases
   Name    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------
 omm       | omm   | UTF8     | C       | C     | 
 postgres  | omm   | UTF8     | C       | C     | 
 template0 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
 template1 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
(4 rows)
----------------创建数据库musicdb10
omm=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb10  WITH TABLESPACE = music_tbs;
CREATE DATABASE
---------------创建用户user10
omm=# CREATE USER user10 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
omm=# CREATE ROLE
-----------------赋予sysadmin权限
omm=# ALTER USER user10 SYSADMIN;
omm=# 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=> 
openGauss=>  create table t11(col1 char(20));
CREATE TABLE
openGauss=> insert into t11 values('Hello openGauss! 11');
INSERT 0 1
openGauss=>  select * from t11;  
         col1         
----------------------
 Hello openGauss! 11 
(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=> 
omm=> create table t21(col1 char(20));
CREATE TABLE
omm=> insert into t21 values('Hello openGauss! 21');
INSERT 0 1
omm=>  select * from t21;
         col1         
----------------------
 Hello openGauss! 21 
(1 row)

4.用户user10访问数据库musicdb10，创建一个表并插入数据

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 t31(col1 char(20));
musicdb10=> CREATE TABLE
musicdb10=>  insert into t31 values('Hello openGauss! 31');
musicdb10=> INSERT 0 1
musicdb10=>  select * from t31;
musicdb10=>          col1         
----------------------
 Hello openGauss! 31 
(1 row)