openGauss每日一练 第3天 数据库

学习感受

继续学习，坚持就是胜利！
感觉实训平台还是很好用的，学习SQL语句来简单高效！！

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

课后作业

连接openGauss

#第一次进入等待15秒
#数据库启动中…
su - omm
gsql -r

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+

4.在数据库tpcc2中创建customer表，字段自定义

\c tpcc2
CREATE TABLE products 
( product_id             integer,   
  product_name           char(30),    
  category               char(20) 
);

5.删除新创建的数据库

drop database tpcc10;
\l
drop database tpcc2;
-- 会报错，ERROR:  cannot drop the currently open database
-- 切换到其他数据库再删除
\c 其他数据库
drop database tpcc2;
\l

6.退出gsql程序

\q

作业执行结果：

omm=# create database tpcc1;
CREATE DATABASE
omm=# create database tpcc2;
CREATE DATABASE
omm=# alter database tpcc1 rename to tpcc10;
ALTER DATABASE
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
 tpcc10    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
(6 rows)

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 products 
tpcc2-# ( product_id             integer,   
tpcc2(#   product_name           char(30),    
tpcc2(#   category               char(20) 
tpcc2(# );
CREATE TABLE
tpcc2=# 
tpcc2=# \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
 tpcc10    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
(6 rows)

tpcc2=# \l+
                                                               List of databases
   Name    | Owner | Encoding |   Collate   |    Ctype    | Access privileges | Size  | Tablespac
e |                Description                 
-----------+-------+----------+-------------+-------------+-------------------+-------+----------
--+--------------------------------------------
tpcc2=#  omm       | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_defaul
t | 
 postgres  | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_defaul
t | default administrative connection database
 template0 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +| 10 MB | pg_defaul
t | default template for new databases
           |       |          |             |             | omm=CTc/omm       |       |          
  | 
 template1 | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/omm           +| 10 MB | pg_defaul
t | unmodifiable empty database
           |       |          |             |             | omm=CTc/omm       |       |          
  | 
 tpcc10    | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_defaul
t | 
 tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                   | 10 MB | pg_defaul
t | 
(6 rows)


tpcc2=# drop database tpcc10;
DROP DATABASE
tpcc2=# \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
 tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
(5 rows)

tpcc2=# drop database tpcc2;
ERROR:  cannot drop the currently open database

tpcc2=# \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
 tpcc2     | omm   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
(5 rows)