openGauss每日一练第3天|《学习openGauss创建数据库、修改数据库属性和删除数据库》学习课堂练习和课后练习

openGauss每日一练第3天 《学习openGauss创建数据库、修改数据库属性和删除数据库》学习心得体会感觉国产化数据库更贴近中国人的思想，下面是课堂练习和课后练习

课程学习

连接数据库

#第一次进入等待15秒
#数据库启动中...
su - omm
gsql -r

1.创建数据库

–查看当前服务中有哪几个数据库

\l
omm=# \l
                              List of databases
   Name    | Owner | Encoding |   Collate   |    Ctype    | Access privileges 
-----------+-------+----------+-------------+-------------+-------------------
 omm       | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 postgres  | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 template0 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
 template1 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
(4 rows)

–新创建名为music的数据库

CREATE DATABASE music;

–再次查看当前服务中的数据库，可以查看到新创建的数据库

\l
omm=# CREATE DATABASE music;
CREATE DATABASE
omm=# \l
                              List of databases
   Name    | Owner | Encoding |   Collate   |    Ctype    | Access privileges 
-----------+-------+----------+-------------+-------------+-------------------
 music     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 omm       | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 postgres  | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 template0 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
 template1 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
(5 rows)

2.修改数据库属性

–修改数据库的最大连接数

ALTER DATABASE music CONNECTION LIMIT= 10;

–将music重命名为music1

ALTER DATABASE music RENAME TO music1;

–查看修改成功

\l

omm=# ALTER DATABASE music CONNECTION LIMIT= 10;
ALTER DATABASE
omm=# ALTER DATABASE music RENAME TO music1;
ALTER DATABASE
omm=# \l
                              List of databases
   Name    | Owner | Encoding |   Collate   |    Ctype    | Access privileges 
-----------+-------+----------+-------------+-------------+-------------------
 music1    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 omm       | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 postgres  | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 template0 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
 template1 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
(5 rows)

3.删除数据库

DROP DATABASE music1;

4.在新创建的数据库中创建表

CREATE DATABASE music2;

–进入数据库music2

\c music2;
CREATE TABLE t2(a int, b varchar(10));
omm=# \c music2
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "music2" as user "omm".
music2=# CREATE TABLE t2(a int, b varchar(10));
CREATE TABLE
music2=# \d
                        List of relations
 Schema | Name | Type  | Owner |             Storage              
--------+------+-------+-------+----------------------------------
 public | t2   | table | omm   | {orientation=row,compression=no}
(1 row)

–退出gsql程序

\q

课后作业

1.分别创建名为tpcc1和tpcc2的数据库

create database tpcc1;
create database tpcc2;

2.将tpcc1数据库重命名为tpcc10

alter database tpcc1 rename to tpcc10;

3.分别使用\l和\l+两个元命令查看数据库信息

\l
\l+
omm=# \l
                              List of databases
   Name    | Owner | Encoding |   Collate   |    Ctype    | Access privileges 
-----------+-------+----------+-------------+-------------+-------------------
 music2    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 omm       | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 postgres  | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 template0 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
 template1 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
 tpcc1     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
omm=#  tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
(7 rows)


omm=# \l+
                                                               List of databases
   Name    | Owner | Encoding |   Collate   |    Ctype    | Access privileges | Size  | Tables
pace |                Description                 
-----------+-------+----------+-------------+-------------+-------------------+-------+-------
-----+--------------------------------------------
 music2    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_def
ault | 
 omm       | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_def
ault | 
 postgres  | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_def
ault | default administrative connection database
 template0 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +| 10 MB | pg_def
 template1 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +| 10 MB | pg_def
ault | unmodifiable empty database
           |       |          |             |             | omm=CTc/omm       |       |       
     | 
 tpcc1     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_def
ault | 
 tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_def
ault | 
ault | default template for new databases
           |       |          |             |             | omm=CTc/omm       |       |       
     | 
(7 rows)

4.在数据库tpcc2中创建customer表，字段自定义

\c tpcc2
create table customer(id int);

5.删除新创建的数据库

\c omm
drop database tpcc10;
drop database tpcc2;

6.退出gsql程序

\q