openGauss每日一练第6天 课程笔记和作业

数据库环境

openGauss:2.0.0 - 数据库实训平台

学习目标

学习openGauss创建模式、修改模式属性和删除模式

学习笔记

• 当schema非空时，如果要删除一个schema及其包含的所有对象，需要使用CASCADE关键字

omm=# ALTER SCHEMA ds_new OWNER TO jack;
ALTER SCHEMA
omm=# \dn+ ds_new;
                 List of schemas
  Name  | Owner | Access privileges | Description 
--------+-------+-------------------+-------------
 ds_new | jack  |                   | 
(1 row)

omm=# DROP SCHEMA ds_new;
ERROR:  cannot drop schema ds_new because other objects depend on it
DETAIL:  table ds_new.t1 depends on schema ds_new
HINT:  Use DROP ... CASCADE to drop the dependent objects too.
omm=# DROP SCHEMA ds_new CASCADE;
NOTICE:  drop cascades to table ds_new.t1
DROP SCHEMA
omm=# DROP USER jack;
DROP ROLE

课后作业

1.创建一个名为tpcds的模式

omm=# create schema tpcds;
CREATE SCHEMA
omm=# \dn+
                              List of schemas
    Name     | Owner | Access privileges |           Description            
-------------+-------+-------------------+----------------------------------
 cstore      | omm   |                   | reserved schema for DELTA tables
 dbe_perf    | omm   |                   | dbe_perf schema
 pkg_service | omm   |                   | pkg_service schema
 public      | omm   | omm=UC/omm       +| standard public schema
             |       | =U/omm            | 
 snapshot    | omm   |                   | snapshot schema
 tpcds       | omm   |                   | 
(6 rows)

2.创建一个用户tim, 并将tpcds的owner修改为tim，且修改owner前后分别使用\dn+查看模式信息

omm=# create user tim identified by 'tim-user-pwd-12';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE

omm=# \du
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 gaussdb   | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
 tim       |                                                                                                                  | {}

omm=# alter schema tpcds owner to tim;
ALTER SCHEMA
omm=# \dn+
                              List of schemas
    Name     | Owner | Access privileges |           Description            
-------------+-------+-------------------+----------------------------------
 cstore      | omm   |                   | reserved schema for DELTA tables
 dbe_perf    | omm   |                   | dbe_perf schema
 pkg_service | omm   |                   | pkg_service schema
 public      | omm   | omm=UC/omm       +| standard public schema
             |       | =U/omm            | 
 snapshot    | omm   |                   | snapshot schema
 tim         | tim   |                   | 
 tpcds       | tim   |                   | 
(7 rows)

omm=#                               

3.重命名tpcds为tpcds1

omm=# alter schema tpcds rename to tpcds1;
ALTER SCHEMA

4.在模式tpcds1中建表customer、插入记录和查询记录

omm=# create table tpcds1.customer(customer_id integer,customer_name char(30));
CREATE TABLE
omm=# \d+ tpcds1.customer;
                              Table "tpcds1.customer"
    Column     |     Type      | Modifiers | Storage  | Stats target | Description 
---------------+---------------+-----------+----------+--------------+-------------
 customer_id   | integer       |           | plain    |              | 
 customer_name | character(30) |           | extended |              | 
Has OIDs: no
Options: orientation=row, compression=no

omm=# insert into tpcds1.customer values(1,'hello world');
INSERT 0 1
omm=# select * from tpcds1.customer;
 customer_id |         customer_name          
-------------+--------------------------------
           1 | hello world                   
(1 row)

5.删除模式tpcds1

omm=# drop schema tpcds1;
ERROR:  cannot drop schema tpcds1 because other objects depend on it
DETAIL:  table tpcds1.customer depends on schema tpcds1
HINT:  Use DROP ... CASCADE to drop the dependent objects too.
omm=# drop schema tpcds1 cascade;
NOTICE:  drop cascades to table tpcds1.customer
DROP SCHEMA
omm=# drop user tim;
DROP ROLE
omm=# \dn+
                              List of schemas
    Name     | Owner | Access privileges |           Description            
-------------+-------+-------------------+----------------------------------
 cstore      | omm   |                   | reserved schema for DELTA tables
 dbe_perf    | omm   |                   | dbe_perf schema
 pkg_service | omm   |                   | pkg_service schema
 public      | omm   | omm=UC/omm       +| standard public schema
             |       | =U/omm            | 
 snapshot    | omm   |                   | snapshot schema
(5 rows)


omm=# \du
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 gaussdb   | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}

omm=# 

学习资源

• openGauss SQL学习参考资料
• 每日一练：openGauss数据库在线实训课程
• openGauss每日一练 | 21期养成好习惯，提升技术能力！
• 墨天轮Markdown编辑器使用介绍
• 墨天轮数据库在线实训平台V1.0操作手册
• 墨天轮数据社区

欢迎各位同学一起来交流学习心得！