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-学习笔记

连接数据库
root@modb:~# su - omm
omm@modb:~$ gsql -r
gsql ((openGauss 2.0.0 build 78689da9) compiled at 2021-03-31 21:03:52 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

1.创建数据库
–查看当前服务中有哪几个数据库

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)

omm=# CREATE DATABASE music;
CREATE DATABASE

2.修改数据库属性
–修改数据库的最大连接数

omm=# ALTER DATABASE music CONNECTION LIMIT= 10;
ALTER DATABASE
omm=#

–将music重命名为music1

omm=# ALTER DATABASE music RENAME TO music1;
ALTER DATABASE

–查看修改成功

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
(5 rows)

template1 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/omm +
| | | | | omm=CTc/omm
omm=#

3.删除数据库
omm=# DROP DATABASE music1;
DROP DATABASE
4.在新创建的数据库中创建表
omm=# CREATE DATABASE music2;
CREATE DATABASE
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

课后作业
1.分别创建名为tpcc1和tpcc2的数据库
music2=# create database tpcc1;
CREATE DATABASE
music2=# create database tpcc2;
CREATE DATABASE
2.将tpcc1数据库重命名为tpcc10
music2=# alter database tpcc1 rename to tpcc10;
ALTER DATABASE
3.分别使用\l和\l+两个元命令查看数据库信息
music2=# \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
(7 rows)

tpcc10 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
tpcc2 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
music2=# \l+
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges | Size | Tablespace | Description
-----------+-------+----------+-------------+-------------+-------------------+-------+------------+--------------------------------------------
music2 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 10 MB | pg_default |
omm | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 10 MB | pg_default |
postgres | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 10 MB | pg_default | default administrative connection database
template0 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/omm +| 10 MB | pg_default | default template for new databases
| | | | | omm=CTc/omm | | |
template1 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/omm +| 10 MB | pg_default | unmodifiable empty database
| | | | | omm=CTc/omm | | |
tpcc10 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 10 MB | pg_default |
tpcc2 | omm | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | 10 MB | pg_default |
(7 rows)
4.在数据库tpcc2中创建customer表，字段自定义
music2=# \c tpcc2
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "tpcc2" as user "omm".
tpcc2=# CREATE TABLE t2(a int, b varchar(10));
CREATE TABLE
5.删除新创建的数据库
tpcc2=# \c omm
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "omm" as user "omm".
omm=# drop database tpcc2;
DROP DATABASE
omm=# drop database tpcc10;
DROP DATABASE
6.退出gsql程序
omm=# \q