openGauss每日一练 第6天 SCHEMA模式

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

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

课后作业

1.创建一个名为tpcds的模式

CREATE schema tpcds;

\dn+ tpcds

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

create user tim PASSWORD 'abcd@123';
alter schema tpcds OWNER to tim;

\dn+

3.重命名tpcds为tpcds1

alter schema tpcds rename to tpcds1;

4.在模式tpcds1中建表customer、插入记录和查询记录

\dn+ tpcds1;
CREATE TABLE tpcds1.customer
(  c_customer_sk             integer,   
  c_customer_id             char(5),    
  c_first_name              char(6),    
  c_last_name               char(8) 
) ;

\d+ tpcds1.customer;

INSERT INTO customer (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES (3769, 5, 'Grace','White');
INSERT INTO customer (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES    
(6885, 1, 'Joes', 'Hunter'),    
(4321, 2, 'Lily','Carter'),    
(9527, 3, 'James', 'Cook'),
(9500, 4, 'Lucy', 'Baker');

select * from  customer;


\dn+

5.删除模式tpcds1

\dn
drop schema tpcds1;
-- –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 tpcds1 CASCADE;
DROP USER tim;
\dn

作业执行结果

omm=# CREATE SCHEMA ds;
CREATE SCHEMA
omm=# \dn+ ds;
                List of schemas
 Name | Owner | Access privileges | Description 
------+-------+-------------------+-------------
 ds   | omm   |                   | 
(1 row)

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

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

omm=# CREATE USER jack PASSWORD 'abcd@123';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
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 USER jack;DROP SCHEMA