openGauss每日一练第3天|openGauss创建数据库、修改数据库属性和删除数据库

学习目标

学习openGauss创建数据库、修改数据库属性和删除数据库

课程学习

连接数据库

#第一次进入等待15秒
#数据库启动中...
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)

–新创建名为music的数据库

omm=# CREATE DATABASE music;
CREATE DATABASE

–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

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

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

–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
 template1 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +
           |       |          |             |             | omm=CTc/omm
(5 rows)

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

–进入数据库music2

omm=# \c music2
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

–退出gsql程序

music2=# \q
omm@modb:~$

课后作业

1.分别创建名为tpcc1和tpcc2的数据库

omm=# create database tpcc1;
CREATE DATABASE
omm=# create database tpcc2;
CREATE DATABASE

2.将tpcc1数据库重命名为tpcc10

omm=# 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

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       | 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
 tpcc10    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
(7 rows)omm=# \l+
iption                 
-----------+-------+----------+-------------+-------------+-------------------+-------+------------+---------------------
-----------------------
 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 administrati
ve 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 d
atabase
           |       |          |             |             | omm=CTc/omm       |       |            | 
 tpcc10    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_default | 
                                                               List of databases
   Name    | Owner | Encoding |   Collate   |    Ctype    | Access privileges | Size  | Tablespace |                Descr

 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

omm=# \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 customer(c_id int);
CREATE TABLE
tpcc2=# \d 
                          List of relations
 Schema |   Name   | Type  | Owner |             Storage              
--------+----------+-------+-------+----------------------------------
 public | customer | table | omm   | {orientation=row,compression=no}
(1 row)

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".
tpcc2=# drop database tpcc10;
DROP DATABASE
omm=# drop database tpcc2;
omm=# DROP DATABASE

6.退出gsql程序

omm=# \q
omm@modb:~$