openGauss每日一练第6天 | 学习心得体会

学习目标

学习openGauss创建模式、修改模式属性和删除模式

课程学习实操

模式是一组数据库对象的集合，主要用于控制对数据库对象的访问

连接openGauss

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

–创建名为ds的模式

CREATE SCHEMA ds;
omm=# CREATE SCHEMA ds;
CREATE SCHEMA
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–查看ds模式信息, owner为omm

\dn+ ds;
omm=# \dn+ ds;
                List of schemas
 Name | Owner | Access privileges | Description 
------+-------+-------------------+-------------
 ds   | omm   |                   | 
(1 row)
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2.在ds中建表

create table ds.t1(id int, name char(30));
insert into ds.t1 values(1 ,'xxxx');
select * from ds.t1;
omm=# create table ds.t1(id int, name char(30));
omm=# insert into ds.t1 values(1 ,'xxxx');
CREATE TABLE
INSERT 0 1
omm=# select * from ds.t1;
 id |              name              
----+--------------------------------
  1 | xxxx                          
(1 row)

omm=# 
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–查看表信息

\d+ ds.t1;
omm=# \d+ ds.t1;
                               Table "ds.t1"
 Column |     Type      | Modifiers | Storage  | Stats target | Description 
--------+---------------+-----------+----------+--------------+-------------
 id     | integer       |           | plain    |              | 
 name   | character(30) |           | extended |              | 
Has OIDs: no
Options: orientation=row, compression=no

omm=# 
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3.修改模式信息

–重命名模式为ds_new

ALTER SCHEMA ds RENAME TO ds_new;
select * from ds_new.t1;
omm=# ALTER SCHEMA ds RENAME TO ds_new;
ALTER SCHEMA
omm=# select * from ds_new.t1;
 id |              name              
----+--------------------------------
  1 | xxxx                          
(1 row)
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–创建用户jack

CREATE USER jack PASSWORD 'abcd@123';
omm=# CREATE USER jack PASSWORD 'abcd@123';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# 
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–将ds_new的所有者修改为jack

ALTER SCHEMA ds_new OWNER TO jack;
omm=# ALTER SCHEMA ds_new OWNER TO jack;
ALTER SCHEMA
omm=# 
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–查看ds_new模式信息

\dn+ ds_new;
omm=# \dn+ ds_new;
                 List of schemas
  Name  | Owner | Access privileges | Description 
--------+-------+-------------------+-------------
 ds_new | jack  |                   | 
(1 row)
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4.删除模式

DROP SCHEMA ds_new;
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.
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–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

DROP SCHEMA ds_new CASCADE;
DROP USER jack;omm=# DROP SCHEMA ds_new CASCADE;
NOTICE:  drop cascades to table ds_new.t1
DROP SCHEMA
omm=# DROP USER jack;
DROP ROLE
omm=# 

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课后作业

1.创建一个名为tpcds的模式

omm=# CREATE SCHEMA tpcds;
CREATE SCHEMA
omm=# 
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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 password '@163.com';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# 
omm=# \dn+ tpcds
                 List of schemas
 Name  | Owner | Access privileges | Description 
-------+-------+-------------------+-------------
 tpcds | omm   |                   | 
(1 row)
omm=# alter schema tpcds owner to tim;
ALTER SCHEMA
omm=# 
omm=# \dn+ tpcds
                 List of schemas
 Name  | Owner | Access privileges | Description 
-------+-------+-------------------+-------------
 tpcds | tim   |                   | 
(1 row)
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3.重命名tpcds为tpcds1

omm=# alter schema tpcds rename to tpcds1;
ALTER SCHEMA
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4.在模式tpcds1中建表customer、插入记录和查询记录

omm=# create table tpcds1.customer (id integer, name varchar(30), address varchar(60));
CREATE TABLE
omm=# insert into tpcds1.customer values (1,'Sean','Futian');
INSERT 0 1omm=#  insert into tpcds1.customer values (2,'Leton','Luohu');
INSERT 0 1
omm=# select * from tpcds1.customer;
 id | name  | address 
----+-------+---------
  1 | Sean  | Futian
  2 | Leton | Luohu
(2 rows)
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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=# 
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学习总结

通过本节课的学习,我学会了创建模式、修改模式属性和删除模式。