openGauss每日一练第4天 | 学习心得体会

学习openGauss体系结构，使用多个用户访问同一个数据库
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。
创建表默认Schema对象为公共对象，该数据库下所有用户创建表使用所有用户都查询可见。

在作业部分中，创建表数据时出现了一个疑问，我使用复制命令的时候，没有复制成功查询命令；
仍然粘贴执行了insert插入数据，并且数据内容与上一条插入语句内容完全一致，导致该表出现了重复数据，是否在建表时需要对创建列字段做重复数据限制？这是应该在建表时限制，还是应该在做SQL插入时做复查更新？

1.测试环境准备

omm=# \l
 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

omm=# drop DATABASE  IF EXISTS  musicdb;
NOTICE:  database "musicdb" does not exist, skipping
omm=# DROP DATABASE
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.
omm=# DROP TABLESPACE

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

omm=# \l
 musicdb   | omm   | UTF8     | C       | C     | 
 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
omm=# 

2.创建用户user1、user2、user3

omm=# \du
 gaussdb   | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
 user1     |                                                                                                                  | {}
 user2     |                                                                                                                  | {}
 user3     |                                                                                                                  | {}

omm=# omm=# 

omm=# ALTER USER user1 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user2 SYSADMIN;
ALTER ROLE
omm=# ALTER USER user3 SYSADMIN;
ALTER ROLE
omm=# 
omm=# 
omm=# 
omm=# \du
 gaussdb   | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
 user1     | Sysadmin                                                                                                         | {}
 user2     | Sysadmin                                                                                                         | {}
 user3     | Sysadmin 

3.在终端中，分别使用user1、user2、user3用户访问数据库musicdb。
–以用户user1的身份在数据库musicdb中创建表t1，并插入一条数据：

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;
 Hello kunpeng 1

–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: 
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;
 Hello kunpeng 2 

–以用户user3的身份在数据库musicdb中创建表t3，并插入一条数据：

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;
 Hello kunpeng 3  

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：

musicdb=> \dt
 public | t1   | table | user1 | {orientation=row,compression=no}
 public | t2   | table | user2 | {orientation=row,compression=no}
 public | t3   | table | user3 | {orientation=row,compression=no}

musicdb=> \q
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=# \dt
No relations found.
omm=# \l
                         List of databases
   Name    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------
 musicdb   | omm   | UTF8     | C       | C     | 
 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
(5 rows)

omm=# \c musicdb
musicdb=# Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb" as user "omm".

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)

作业记录：

omm-# \l
                         List of databases
   Name    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------
 musicdb   | omm   | UTF8     | C       | C     | 
 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
(5 rows)
omm=# CREATE TABLESPACE music_tbs2 RELATIVE LOCATION 'tablespace2/test_ts2';
omm=# CREATE TABLESPACE
omm=# \db
            List of tablespaces
    Name    | Owner |       Location       
------------+-------+----------------------
 music_tbs  | omm   | tablespace/test_ts1
 music_tbs2 | omm   | tablespace2/test_ts2
 pg_default | omm   | 
 pg_global  | omm   | 
(4 rows)

omm=# CREATE DATABASE musicdb2  WITH TABLESPACE = music_tbs2;
CREATE DATABASE
musicdb2=>  product_id | product_name | category 
------------+--------------+----------
(0 rows)


musicdb2=> 
musicdb2=> 
musicdb2=>   insert into test1 values(1502,'olympus camera','electrncs'),(1601,'lamaze',ce','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb2=> musicdb2=> 

musicdb2=> 
musicdb2=> 
musicdb2=> 
musicdb2=>   insert into test1 values(1502,'olympus camera','electrncs'),(1601,'lamaze',ce','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb2=> 
musicdb2=> select * from test1;
 product_id |     product_name     |            category            
------------+----------------------+--------------------------------
       1502 | olympus camera       | electrncs                     
       1601 | lamaze               | toys                          
       1700 | wait interface       | Books                         
       1666 | harry potter         | toys                          
       1502 | olympus camera       | electrncs                     
       1601 | lamaze               | toys                          
       1700 | wait interface       | Books                         
       1666 | harry potter         | toys                          
(8 rows)

musicdb2=> \c musicdb2 user2
Password for user user2: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user2".
musicdb2=>  create table test2(product_id INTEGER,product_name Char(20),category Char(30));
musicdb2=> CREATE TABLE
  insert into test2 values(1502,'olympus camera','electrncs'),(1601,'lamaze','toys'),(17ce','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb2=>   select * from test2;
 product_id |     product_name     |            category            
------------+----------------------+--------------------------------
       1502 | olympus camera       | electrncs                     
       1601 | lamaze               | toys                          
       1700 | wait interface       | Books                         
       1666 | harry potter         | toys  

musicdb2=> \c musicdb2 user3
Password for user user3: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb2" as user "user3".
musicdb2=> create table test3(product_id INTEGER,product_name Char(20),category Char(30));
CREATE TABLE
musicdb2=>   insert into test3 values(1502,'olympus camera','electrncs'),(1601,'lamaze',ce','Books'),(1666,'harry potter','toys');
INSERT 0 4
musicdb2=>   select * from test3;
 product_id |     product_name     |            category            
------------+----------------------+--------------------------------
       1502 | olympus camera       | electrncs                     
       1601 | lamaze               | toys                          
       1700 | wait interface       | Books                         
       1666 | harry potter         | toys                          
(4 rows)

musicdb2=> \dt
                         List of relations
 Schema | Name  | Type  | Owner |             Storage              
--------+-------+-------+-------+----------------------------------
 public | test1 | table | user1 | {orientation=row,compression=no}
 public | test2 | table | user2 | {orientation=row,compression=no}
 public | test3 | table | user3 | {orientation=row,compression=no}
(3 rows)