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。

1.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 musicdb1  WITH TABLESPACE = music_tbs;
CREATE DATABASE musicdb2  WITH TABLESPACE = music_tbs;
CREATE DATABASE musicdb3  WITH TABLESPACE = music_tbs;

--执行下面的SQL语句，创建用户user1：

 CREATE USER user1 IDENTIFIED BY 'kunpeng@1234';
 
--授予user1数据库系统的SYSADMIN权限：

ALTER USER user1 SYSADMIN;

 2.使用数据库用户user1登录到数据库musicdb1，创建一个表t11，并插入一条数据：

--用户user1登录到数据库musicdb1，创建表t11，并插入、查看数据

 \c musicdb1 user1

 create table t11(col1 char(20));
 insert into t11 values('Hello openGauss! 11');
 select * from t11;      

3.使用数据库用户user1登录到数据库musicdb2，创建一个表t21，并插入一条数据：

--用户user1登录到数据库musicdb2，创建表t21，并插入、查看数据
  \c musicdb2 user1

 create table t21(col1 char(20));
 insert into t21 values('Hello openGauss! 22');
 select * from t21;

4.使用数据库用户user1登录到数据库musicdb3，创建一个表t31，并插入一条数据：

–用户user1登录到数据库musicdb3，创建表t31，并插入、查看数据
  \c musicdb3 user1

 create table t31(col1 char(20));
 insert into t31 values('Hello openGauss! 33');
 select * from t31;

课程作业

1.进入数据库环境后进性环境检查

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=#omm=# \db
      List of tablespaces
    Name    | Owner | Location 
------------+-------+----------
 pg_default | omm   | 
 pg_global  | omm   | 
(2 rows)

omm=# \du  
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 gaussdb   | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}

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)

2.创建数据库musicdb10，创建用户user10，赋予sysadmin权限

omm=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts10';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb10  WITH TABLESPACE = music_tbs;
CREATE DATABASE
omm=#  CREATE USER user10 IDENTIFIED BY 'xiaocx_1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# ALTER USER user10 SYSADMIN;
ALTER ROLE

3.用户user10访问数据库postgres，创建一个表并插入数据

musicdb10=> \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 postgres_u10(id int,name char(20));
CREATE TABLE
openGauss=>  insert into postgres_u10 values(1,'xiaocx1');
INSERT 0 1
openGauss=>  insert into postgres_u10 values(2,'xiaocx2');
INSERT 0 1
openGauss=>  insert into postgres_u10 values(3,'xiaocx3');
INSERT 0 1
openGauss=>  insert into postgres_u10 values(4,'xiaocx4');
INSERT 0 1
openGauss=>  insert into postgres_u10 values(5,'xiaocx5');
INSERT 0 1
openGauss=>--检查验证：
openGauss=>  \dt
                             List of relations
 Schema |     Name     | Type  | Owner  |             Storage              
--------+--------------+-------+--------+----------------------------------
 public | postgres_u10 | table | user10 | {orientation=row,compression=no}
(1 row)

openGauss=>  select * from postgres_u10;
 id |         name         
----+----------------------
  1 | xiaocx1             
  2 | xiaocx2             
  3 | xiaocx3             
  4 | xiaocx4             
  5 | xiaocx5             
(5 rows)

openGauss=> 

4.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 omm_u10(id int,name char(20));
CREATE TABLE
omm=>  insert into omm_u10 values(1,'xiaocx1');
INSERT 0 1
omm=>  insert into omm_u10 values(2,'xiaocx2');
INSERT 0 1
omm=>  insert into omm_u10 values(3,'xiaocx3');
INSERT 0 1
omm=>  insert into omm_u10 values(4,'xiaocx4');
INSERT 0 1
omm=>  insert into omm_u10 values(5,'xiaocx5');
INSERT 0 1
omm=>--检查验证：
omm=>   \dt
                          List of relations
 Schema |  Name   | Type  | Owner  |             Storage              
--------+---------+-------+--------+----------------------------------
 user10 | omm_u10 | table | user10 | {orientation=row,compression=no}
(1 row)

omm=>  select * from omm_u10;
 id |         name         
----+----------------------
  1 | xiaocx1             
  2 | xiaocx2             
  3 | xiaocx3             
  4 | xiaocx4             
  5 | xiaocx5             
(5 rows)

omm=> 

5.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 musicdb10_u10(id int,name char(20));
CREATE TABLE
musicdb10=>  insert into musicdb10_u10 values(1,'xiaocx1');
INSERT 0 1
musicdb10=>  insert into musicdb10_u10 values(2,'xiaocx2');
INSERT 0 1
musicdb10=>  insert into musicdb10_u10 values(3,'xiaocx3');
INSERT 0 1
musicdb10=>  insert into musicdb10_u10 values(4,'xiaocx4');
INSERT 0 1
musicdb10=>  insert into musicdb10_u10 values(5,'xiaocx5');
INSERT 0 1musicdb10=>

--检查验证：musicdb10=> \dt
                             List of relations
 Schema |     Name      | Type  | Owner  |             Storage              
--------+---------------+-------+--------+----------------------------------
 public | musicdb10_u10 | table | user10 | {orientation=row,compression=no}
(1 row)

musicdb10=> select * from musicdb10_u10;
 id |         name         
----+----------------------
  1 | xiaocx1             
  2 | xiaocx2             
  3 | xiaocx3             
  4 | xiaocx4             
  5 | xiaocx5             
(5 rows)

musicdb10=>