openGauss每日一练第4天 | 学习心得体会

1.测试环境准备：

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=# drop DATABASE IF EXISTS musicdb;
NOTICE: database "musicdb" does not exist, skipping
DROP DATABASE
omm=# drop DATABASE IF EXISTS musicdb;
NOTICE: database "musicdb" does not exist, skipping
DROP DATABASE
omm=# drop DATABASE IF EXISTS musicdb1;
NOTICE: database "musicdb1" does not exist, skipping
DROP DATABASE
omm=# drop DATABASE IF EXISTS musicdb2;
NOTICE: database "musicdb2" does not exist, skipping
DROP DATABASE
omm=# drop DATABASE IF EXISTS musicdb3;
NOTICE: database "musicdb3" does not exist, skipping
DROP DATABASE
omm=# drop tablespace IF EXISTS music_tbs;
NOTICE: Tablespace "music_tbs" does not exist, skipping.
DROP TABLESPACE

omm=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb WITH TABLESPACE = music_tbs;
CREATE DATABASE

2.创建用户user1、user2、user3

--执行下面的SQL语句，创建用户user1、user2、user3：

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

--授予user1、user2、user3数据库系统的SYSADMIN权限： 

omm=# ALTER USER user1 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user2 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user3 SYSADMIN;
ALTER ROLE
omm=# 

--执行下面的命令，查看有哪些用户： 

omm=# \du

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 | {}
user1 | Sysadmin
| {}
user2 | Sysadmin
| {}
user3 | Sysadmin
| {}

在终端中，分别使用user1、user2、user3用户访问数据库musicdb。

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 products1(product_id int,product_name char(20),category char(30));

CREATE TABLE
musicdb=> insert into products1 values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb=> 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)

--以用户user2的身份在数据库musicdb中创建表t2，并插入一条数据： 

musicdb=> \c musicdb user2
Password for user user2:
FATAL: Invalid username/password,login denied.
Previous connection kept
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');

musicdb=> create table products2(product_id int,product_name char(20),category char(30));
CREATE TABLE
musicdb=> insert into products2 values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys')
musicdb-> ;
INSERT 0 4
musicdb=> 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)

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=> create table products1(product_id int,product_name char(20),category char(30));
CREATE TABLE

musicdb=> create table products3(product_id int,product_name char(20),category char(30));
CREATE TABLE
musicdb=> insert into products3 values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(1700,'wait interface','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb=> select * from products;3; product_id | product_name | category
------------+----------------------+--------------------------------
1502 | olympus camera | electrncs
1601 | lamaze | toys
1700 | wait interface | Books
1666 | harry potter | toys
(4 rows)

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：

musicdb=> \dt
List of relations
Schema | Name | Type | Owner | Storage
--------+-----------+-------+-------+----------------------------------
public | products1 | table | user1 | {orientation=row,compression=no}
public | products2 | table | user2 | {orientation=row,compression=no}
public | products3 | table | user3 | {orientation=row,compression=no}
(3 rows)

musicdb=>